The first thing to notice from the picture in the post below is the dps figures (forgive our pally who was healing at the end!). This fight gets more and more chaotic as time goes on, and the quicker you can get him down the less likely you are to stuff up.
We tanked him near the bottom of the stairs (the old strategy of tanking him at one side no longer works since the most recent patch). The thing to make sure is that you have a bit of space behind you (I'll come onto why later).
In phase 1 dps him down as normal and pop heroism as you enter the heart phase. You only need 1 tank - taunt or heroic throw any Pummellers who appear and tank them with the boss. Once the heart is dead your ranged dps should kill the bomb bots and melee dps should kill the pummellers. You can pretty much ignore the scrap bots as the boss will heal to full anyway.
Once all the adds are dead you can get cracking on the boss. The tantrums are a little more than a minute apart, so I used shield wall and last stand alternately to give the healers a break. The boss hits like a truck in this phase but with good healers this will only be an issue if your healers get bombed or after a tantrum.
When anyone gets light bombed they should run around the group in an arc until they are standing behind you. When the light spark spawns you taunt it and put a little threat on it so that it sticks to you while the dpsers kill it. You need to pick one or two of the dpsers to nuke down the sparks - a hunter or someone else with instant attacks is good for this. It helps to have nameplates enabled so that you can see the sparks when they appear.
When anyone gets gravity bombed they just need to run away from the group and drop their void zone.
The main things that can go wrong here are someone getting a light bomb and not running behind you - this can mean the spark spawns out of your taunt range and can run amok nuking healers. You can also be unlucky and have your healers bombed just before a tantrum which can cause problems.
It's very hectic as a tank since you are constantly switching targets and checking for light sparks spawning while trying to maintain a strong threat lead and keep the boss debuffed.
(Got saved by my blood draining enchant on the kill again. Love that enchant.)