As much as I'd like the idea of Azjol'Nerub being a raid... I can't actually remember anyone specifically saying Yogg-Saron is supposed to be in there. The only really clear refferences are Vordrassil's roots, as explained by Ursoc, and some statement Anub'arak makes in TFT about his people stumbling onto an old god while they dug. And we have no idea how much either Vordrassil's roots or the Nerubians' digging extends under Northrend, unless I'm mistaken.

Right, I think Yogg-Saron fits in decently enough in Ulduar, that's just not how this story was supposed to end originally.

And I doubt that Loken believed that Yogg-Saron was his father, or anything other than... Yogg-Saron. I mean, maybe if Thorim is ranting about Yogg-Saron being his wife.. I find it much easier to believe that it's just old text that should have been removed, like the references to Kronus.

There was a confirmed Azjol-Nerub raid, and it was confirmed that it would house an Old God. (Back in the day, there was even going to be an Utgarde Keep raid..) It was mentioned back at Blizzcon 2007, so it's hard to find direct quotes, best I could do is dig up someone's recalling of the discussion of Azjol-Nerub:

Blizzcon 2007 Summary - TKA Something (Search "Old God")

Back to more general Old Gods questioning, I finally read the War of the Ancients trilogy this week, and there was a passage that caught my eye (The Sundering, ch. 10, p. 580 - single volume edition):

So the obvious question is: how does this fit with what we're seeing in WoW, if at all? Or has this been retconned in another publication, or in game? Because, well, if the Old Gods are more powerful than Sargeras, then there's something very wrong about the C'Thun we fought, or the YS that we might fight (not to mention the supposed old god in Darkshore).

I've been thinking about this myself as to whether Ulduar was retconned to house Yogg-Saron after Azjol'nerub effectively got scrapped. Ulduar's map files have been in the game since WotLK's alpha in May 2008, so obviously a lot could have changed since then. For the most part, though, the layout is pretty much the same. The frozen hallway, conservatory of life, and arena were all there way back when, so I imagine that these were designed to house the watchers (Mimiron's wing wasn't close to done at that point).

The major difference is what is in the center of the hub. In earlier versions, there was a very large placeholder statue in the middle with a very deep pit around it that did not look like it was designed to be entered. Furthermore, the southwest wing off that hub (which looks to now lead down to the pit) used to actually lead to a big statue that could be walked through and looped back around to a small balcony overlooking the hub on the west wall (which is now a blank empty wall with a curtain hanging on it).

Here's the catch though, in the teaser video, you can see an updated statue in that room, most noticeably visible in the shot rotating around the constellation statue in the antechamber. The statue may be there in the final version, but gets destroyed or something as we progress through the dungeon. Or maybe that's just really old footage.

EDIT - Qaeynin is the Ulduar thread points out that the statue that I'm referring to in the video is actually Kologarn. And now that I think about it, you may fight him at that pit where there is a temporary bridge. Killing him makes the bridge

It already confirmed based on the model in patch file that this statue IS Kologarn, who gate the entrance into the inner Ulduar after antechamber before The Shattered Walkway

Then after The Shattered Walkway you get into the central room, it has nothing to do with the pit

C'Thun was also not imprisoned. He fell in battle, was severely injured, and was in the process of regenerating.

It is probably very safe to assume we didnt actually meet an old god at their full strength yet. C'thun was severely weakened. And I'm pretty sure the imprisonment didn't do much good for the power of the remaining 3 old gods either. The titans probably didn't go 1 on 1 with the old gods and most likely won by taking them out through outnumbering them.

I thought the old Gods and Titans were of roughly comparable strength and that the Titans only came out ahead due to thier numbers.

Sargeras was a powerful Titan warrior at one point, but it makes sense that he was not absurdly more powerful then any other Titan, a few Old Gods would still spell trouble for him head on. But what is more interesting is how Sargeras operates, others do his bidding, he is very much reliant on the burning legion to carry out his plans.

Solo Sargeras wouldn't be anywhere near the threat he is and the other Titans would probably stomp him out, except for his massive army of evil bastard demons that are totally corrupt. Which to me would make influencing them quite easy. My bet is that the main threat from the Old Gods to Sargeras is they could easily turn vast amounts of his army against him.

Well, the thing is, Sargeras might operate more subtly and send his Burning Legion ahead, but that doesn't make him any less powerful. Sargeras probably had to put up quite a display of power only to gain control over them. The Legion leadership is based very much on treachery, even amongst themselves, and surely if his direct subordinates felt Sargeras was an easy prey, he wouldn't have lasted long enough in his position. However, the intent is clearly there; I'm sure every demon out there would love nothing more than to replace Sargeras, and the Old Gods would clearly play that card.

BUT the titans won by outnumbering the Old Gods, and there can't really be that many titans around. Now, the Old Gods may have had massive armies, but so did the titans, I imagine. Eventually, it would still end up as a showdown between the leaders, because, the standard rank and file troops would probably get in the way more than help (and I can actually imagine a score of Earthen trying to enter C'thun's room :P).

Can anyone explain why are the Watchers (Hodir, Freyja etc.) Actively Preventing us from fighting Yog-Sarron? Is it because they are brainwashed or because they don't want raiders to kill him becuase he is quintessential to the order of the universe (or some other nonsense)? And from what I hear in the PTR, since these bosses drop chests for their loot, could it be that they help later on with the fights and they dont actually die on "our" collective hands? I suppose most of the fights are fore-warned by the big chain quest on Storm-peaks finishing with cutting out Loken's tongue (Nice!)

I wonder since Algalon has access to Ulduar and presumably Uldaman and Uldum if we are able to figure out "how" he is able to gain access either through an ability, key, or passageway. I wonder this because if he is supposed to "observe" Azeroth then clearly his intentions are to view all 3 of these areas and gaining knowledge of how he can enter these areas would help in gaining access to Uldum.

If the characters like Brann go in this direction of thinking, then this boss could be a hint of Uldum as the surprise raid or just an added area in the next expansion. But, clearly since you need to have the Plates of Uldum as per The Stone Watcher, then I'm thinking he most likely has the plates for each area.

Or since we save the Ulduar Watchers they are kind enough to let us have passageway into Uldum. It seems wierd that we would go from Ulduar to Uldum, but with the damaged entrance it clearly shows that it could have nothing at all to do with titans anymore and only the structure and design of the instance or area is a resemblance that titans were once there and now something else is.