Yogg+0 discussion is not allowed.

Here is a link that may help you (and other people considering to start yogg+0) though: Fusion’s Yogg Saron mod « StratFu

*Please delete*

Are there bugs related to the number of exit portals when reaching the brain room? On our only 10-man kill we ended up having to use three going into the portals because when we sent in four people we would inconsistently wind up with only three exit portals (I'm not sure on which visions this happened), and one person would go insane because they were stuck in the room. I'm starting to doubt our group sanity though (heh) because every guide I've read indicates that four DPS in the brain room is optimal.

Exit portals don't vanish when you use them, whoever got insane just messed up and used some stupid excuse.

edit: now yogg+0 discussion is open, to save everyone some time: since 3.2, yogg+0 is like yogg+1, just with people taunting the Marked Immortals out before they explode (hunters, offtank, dk, holy pala, whatever) and then having your tanks taunt them back once they explode and less mistakes.

We found DK's to be the worst add tank, and palas the best (quite obvious). We used 2 hunters and a warrior to taunt mobs out. Got our kill around the 5th explosion, longest we've survived without messing up was 7 explosions, but I'm sure you can reach more if you don't mess up. (same thing as yogg+1; going insane, etc)
Aura mastery on the silence helps a lot as well. (= 2 holy paladins)

If you're failing to kill it with 3 people taunting the marked mobs out in time, you are doing it wrong. If you're not hitting p3, you're messing up on the basic fight mechanics -which happened a lot-, if you're not killing him in p3, you need to either put more dps on yogg, get better tanks (2 prot paladins really is tons easier than anything else) and don't go insane.

We use 2 hunters and 1 DK to taunt mobs off but oftenly we have problem that they target same guardian and then it's to retarget new add.
We use macro like:
/target Chosen Imm
/"put mark if it's unmarked"

Is there any other way to guarantee that 3 people target 3 different mobs with 1 macro?

The link Dalhia posted should give you enough help on this matter. It's about a excellent mod that assists you on the adds.

We also used 2 hunters + a tank to handle the Marked Immortal Guardian. We had the 2 hunters with Slave: Yoggles_Parallel installed and the tank with the Master. Whenever empowerment happened the hunter's would start with spamming /tar Marked Immortal Guardian while we all hover over the nameplates so the mod can mark the adds. The problem with /tar means you will only select the closest mob but it does help with 1 or 2 very fast marks.

The tricky part was finding your mark when you had 10+ health bars all over the place. We countered this by installing Aloft.Aloft (Beta) : WoWInterface Downloads : Beta-version AddOns. Within this mod we changed the size of the icons and frames so it was easier to click on the right one.

We tried Yoggles_Parallel but seems it works only for english version of client (we play on russian client).
We use macro like this:
/tar Chosen
/run local C=GetRaidTargetIndex("target"); if not C then SetRaidTarget("target",1) end

/tar Chosen
/run local C=GetRaidTargetIndex("target"); if not C then SetRaidTarget("target",2) end

/tar Chosen
/run local C=GetRaidTargetIndex("target"); if not C then SetRaidTarget("target",3) end

I just realized that probably with such macro we should use 2 taunters and 1 hunter, not 2 hunters and 1 DK.
Because 2 people staying from different sides marks these mobs immediately and if they can taunt, but not just distract for 6 seconds they can pull mob away from center really quick. And after that hunter who stays almost in melee to big group just use macro and choose 3rd mob from pack (because 1st and 2nd will be far away already).

A small question about P3 Alone - how do you deal with threat from AOE? It seems to be one of last limiting factors for us - random AOE'ers get killed by fresh adds, especially mages if they get LB explosions at exactly the wrong moment. On the other hand, being too slow results in tank gibs, so we can't really take breaks whenever new add spawns - especially due to nature of LBs. Some of that could be dealt with using Vigilance/Salvation, but that's not really enough. It's especially bad if adds spawn in some remote location(with boss model obstructing view it happens quite often) so they get picked up very late. These random deaths add up fast and eventually we can't keep up with Beacon healing.

What we do to prevent this (and also healer gibs) is stack up the whole raid on a protection paladin. He will pick up every add before it even reaches the raid. A second tank then taunts one off of him, set a mark on it and we focus down the marked one.

Tell your tanks to get some sort of aggro warnings on their unit frames (grid has a plugin for this I believe), so they can see if people have aggro from far away adds and respond accordingly.

That's 10 man I take it. Single add is not a problem, that can be easily focus fired. But with 3 of those on 50% and fresh one on 100% - plus likely another one being quite high since he spawned right before beacons, it gets bit messy. If anything, I find clumping them on tanks to be more dangerous since threat cap is 20% lower. Main problem here is, that you cannot taunt them too much or they will be on DR during Beacons, and cutting 50% from Distracting Shot is a lot.
It's not really about grabbing adds, but some random threat spikes from AOE which can result in this.

Tanks should be very attentive on new adds while rogues help them with other mobs FoKing with tricks on CD.