This PS3 vs Xbox 360 talk is so 2007.
Seriously, both conbsoles will sell more than 70 million and that is much more than enough to warrant 3rd party support for a VERY long time.
If you are 3rd party devloper you don't have to make a choice between PS3 vs Xbox 360. Both are more or less equally powerful so the choice basically is: Wii or PS3/Xbox 360/(PC).
The only ones who care for this are we, the fanboys. Every 3rd party developer wants to be on as many platforms as possible, except his game gets published by Sony or MS. (Epic - Gears of War / From Software - Demon Souls for example).
Every major 3rd party franchise will be multiplat anyway. Look at GTA IV as an example: 8.3 million on Xbox 360 and 7.08 million on PS3. Rockstar cannot afford to lose 50% of the sales.
Imagine not having GamePass on your console...
