To point out the obvious, all the top guilds in the world are ... guilds.
When I look at the lists of top 50 to kill boss X, or Boss Y, I dont recall ever seeing a guild alliance. While the reasons for this are pretty self evident it did make me think, how many people here raid as a cross-guild alliance ? And how far have you got ?

How many cross guild alliances survive, and how many collapse into a single guild ?
How many find all their players bleed out, or struggle to recruit because other people arent really sure where to aply to ?
How many pick up recruits specifically becuase you are a cross-guild alliance ?

I think Im really just wondering how many othr people ther are out there "like us", and how they are doing. And perhaps, how they see the expansion affecting us.

There's one 3 guild alliance horde side on my server thats up to Huhuran, and surprisingly enough, they don't really seem to bleed players. Their public attitude is more flippant than most guilds, though I heard they had to buckle down to push through BWL. They're a nice bunch, and seem largely satisfied with what they're doing. One guild does seem to be the de facto center of the alliance though, by virtue of having the most vocal and identifiable guild leader.

We started out as 5 guilds when we were originally on Warsong. We did pretty well for ourselves and got a few server first in BWL. When we transferred, we merged into 2 guilds for a few months. We eventually merged into 1 guild and that's how we've stayed thus far. The biggest reason for the changes were logistics. It was much easier to manage sit out, and recruitement with one guild than it was with 2 or even 5. It just became much easier for the officers to communicate once we were all in the same guild, and officer chat actually became useful for running the raids. There was animosity between certain people before the merger and there still is now that we are one guild. I'm fairly certain that we wouldn't have done as well as we had, if we hadn't merged in the first place. Though I think there's always the chance that leadership might butt heads when trying mergers, but we've been pretty lucky in that our officers have mostly gotten along pretty well. Leadership getting along and not fighting is probably really important to keep a guild from collapsing during a merger.

There's been several guild alliances on my server, I've yet to see one not collapse or merge by about Firemaw.

Alot of the best groups on my server are communities of several guilds.
Granted we are hardly the bleeding edge but most communities have managed to stay as they are for a very long time

Same situation on our server. the top horde raid (7 naxx bosses down) consists of 3 guilds and the top alliance raid (8 naxx bosses down) includes 2 guilds. As you can see, they are also not bleeding edge compared to other servers, but the best on our realm. I'm raiding in a guild alliance too (only up to the twin emps) which consists of one big guild and a smaller one.
I don't know if it has to do with european servers generally being smaller than the US ones. Let's comapre the US Blackrock server with the european one. The US has 35 Nefarian Killing Guilds and 7 C'Thun Killing Guilds, on our server it's about 20-25 and 4 or 5.

On blackrock, of 35 nefarian killing guilds there is 1 alliance left. There were a few raiding alliances that I've seen around which have broken off and gon their own ways. There was one group that was and is reasonably successful, I think due to their small demographic - they were the entirety of the japanese population of the server. They were in about 5 different guilds, and raided as a single entity up until about 2 weeks ago. Their progression was twemps down before they all merged into one big guild. I don't think they could really bleed players, as their players would struggle to communicate with the rest of the server. One of the guilds was called "Japan Alliance" so it would probably be pretty easy for the players joining their guild to find them.

There is one successful guild alliance from my old server (Eredar) with whom most of you should be familiar. The Guardians/Scions of Destiny have been raiding together since the early days of that server, which was 2nd gen.

They boast a world 5th(?) C'thun kill (not that that's a HUGE accomplishment, but w/e) and The Guardians is the home of Veneficus, author of RDX6.

http://www.scionsofdestiny.com/
http://www.guardianhq.com/

These days they are the same entity for all practical purposes, however remain seperate for historical reasons AFAIK. Some of the members of SoD are also more into the RP scene than those of TG I believe.

I would disagree with this.
While this might be special for RP servers due to the fact that many people want to stay in their small rp focused guilds while still raiding.
On our server most communities act as guilds and the only thing that differs from a community and a guild is that you dont get a community tab.

We have one guild on our server that is too small to raid on its own and regularly invites people from other guilds to come with them. I think this has formalised to some extent whereby the main guild only invites proven people from X, Y and Z guilds to its raids. So far they have killed the Twin Emps in AQ and dropped 3 bosses in Naxx.

Also I seem to remember that a Horde based alliance of Tiaria / Orcish Empire from the German EU servers were among the top 5 to kill Nef and C'Thun. I can't remember hearing much from them about Naxx though.

Orcish Empire/Tia'ra were the third guild(s) worldwide, and the first horde to kill nefarian (ahead of DnT btw).
They play on EU-Destromath. Some time ago they merged together and formed the guild Sinwori http://www.sinwori.de/
They have 10 naxx bosses down at the moment. And no I'm not a fanboy ;-) just interessed in well known guilds and their progress.

My current guild was created from the 2 best guilds at the time in a merger close to a year ago. At the time, no one on horde side could push BWL as a single guild so they decided to merge and it worked extremely well.

Argent Dawn has a fairly powerful raiding group that actually started out as a pure PUG.

The Last Horse (The reason for the name should be obvious)

They're 3rd in Alliance raiding currently, having cleared through to C'Thun and working on Naxx Bosses on a regular basis. Its made up of alot of smaller guilds, and guildless folks. Historywise they've always been on the bleeding edge for the content of the game. They joke about it, but the rumor goes that the first Onyxia kill on AD was a direct result of LH getting her down to like 10% before quitting one evening, and the next day the guild to manage the kill first spent the entire day zerging her so the PUG raid didnt beat them. They've never been able to boast of a "First" but they're highly successful in what they do.

My guild started raiding as part of an alliance of us, one other medium-sized guild, and a few smaller guilds. We got to.. Majordomo I think. Then self-destructed, largely over drama caused by a sudden influx of green-geared people in the smaller guilds showing up wanting the easy epics. We recruited a little and carried on alone; the other medium-sized guild carried on in alliance with a couple of the smaller guilds, and later merged with them to form a single guild.

I believe forceful entry use to be several diffrent guilds on warsong known as clown show or something like that. They merged into one guild for convience.

Horde side of Proudmoore put together an alliance of guilds that got several Horde server firsts I believe. If not, they were at least near the front of Horde progression.

I think the key is the same as a successful guild, leadership.

My raid is even stronger segmented than a classical raid alliance. We have players from several guilds who play with us regardless of their guild allegiance and independents. Certainly there are three guilds providing most of the players but guild organisation and raid are two kind of things None of the three core raidleaders do hold an office in their respective guild. Our cohesion mostly stems from our past (our older members are raiding together since june 2005 or so), our and from our success I guess.
Yet we are the most successful raid on our server, claiming most of the first kills and leading in progression (AQ clear except for Viscidous, Naxx 5 bosses down) despite the fact, that our competition is much more rigidly organized and putting up more raidtime than we are (in fact, we are raiding on the weekend and on wednesday, about 20h a week).

It works if you have talented individuals and can cope with the limits of authority you have as a raidleader.

We are a representative-democractically goverened guild alliance of 8 guilds on EU-Thunderhorn who have cleared up to Twin Emps in AQ 40. Most of our drama is handled in the Representative Council (reps) where we have 2 representatives from each guild. It all may seem very very odd, but it actually works. A good guild alliance requires a LOT of work to run (we spend quite some time in meetings).

To make matters worse, our guild alliance is composed of nationality specific guilds: Norwegian, 2xSwedish, Russian, English/belgian, Finish. This makes a common ventrillo/TS server pretty much useless, since the spoke language barrier is quite high. Raiding Loyality is very high, even thou the super-guilds (well, for our standards) were recruting like mad very few core raiders have left our alliance (even thou they have the gear and experience for it).

Most of the guilds in the alliance are based arround real-life friends, so you could say that instead of going out to find new friends most of the players in the alliance just kinda stayed with their real-life friends. Wich is quite different from many guilds.

I can probeably detail a bit more if anyone is interested since it was mostly my brainchild, it's all pretty wierd.

My guild suffered a guild split at one point where we lost most of the raiders. The new 60s and the raiders that were left did not have enough to raid. I think our first raid on Ony or MC post split was with 26 people. We created an alliance with a smaller guild (we had many members, but most were casual or not level 60) that had 20 or so people interested in raiding. It woked out really well and I do not recall any raid problems. The only issued I can think of is that we could not penalize the other guild's players for certain actions because they were not in our guild. Also new 60s in our guild or new recruits would sometimes want the other guilds spots because we were the larger guild and the new players felt that since they (the other guild) were raiding with us that they should have a lower priority for spots and gear and we should only invite them to fill spots. What these people did not understand is that although we were in different guilds, the raiding team was so close that most of us didn't even know which players were in which guilds sometimes, they raiding along side of us and were and are part of the raid team and have equal right to spots and loot. Like we are going to boot some vet raider in the alliance to bring in some noob from our guild, lol. I guess communication could be a small problem considering we did not share the same guild chat, but they heavily used our forum, kept in contact over IM, and hung out on vent with the rest of us.

We started with MC and Ony more than a year ago and downed Huhuran for the first time about a month ago. All in all I think the alliance was a success. We have had our problems in the past, and currently we have some big issues, but I would not attribute them to the guild alliance.

Would form alliance again A++

For a more harcore guild I could see it causing problems due to one guild wanting to progress at a faster rate and possibly wanting to leave the alliance to either raid on their own or with a more progressed guild.

It also might not work if one guild is much farther along in the end game. I could see the more progressed guild blaming wipes on the lack of experience from the other guild. When we formed our alliance most of the players in both guilds had little to no raid exp so we were all kind of learning at the same time. In fact I would say we were all kind of meeting each other at the same time, of course we knew people in our own guild but we had not spent that much time with each other or been on vent with each other until we started raiding.