Blizzard - They are starting to slump a bit, but they are still the most talented group I have seen yet.
Interplay - Barely hanging on by a thread. Don't put too much stock in them. And the developers have begun to revolt (aka Bioware and Prallax/Outrage/Volition)
EA - Going strong but alienating customers of PC Gmaes now.
Sierra - Doing well.
Ubisoft - Doing REALLY well.
Microsoft - Actually, thier division is doing great now that they have some key developers under their belts.
One of the biggest problems I see with the gaming biz right now is piracy. I wish people would stop pirating games, especially if they can afford them. Buying good games let's the developer know it's being purchased, and so to keep making such games. I know games are expensive right now, but that doens't mean you should pirate them to show defiance. Just write the company that games are expensive, and that you would buy them gladly if it were cheaper to do so.