A friend is a writer for games, and has credits over all three systems. Strictly talking between the two, XBOX 360 is easier to code for for the developers, so money and time can be saved by making an exclusive on 360 over PS3. He also says graphically they pretty much are shaping up at the same pace, but the roof has to hit the 360 soon, and the PS3 will pull away... but then hit it's roof, thanks to an inferior GPU. All in all, while the company he works for puts out on both, focus testing is all done on 360.