Well, also consider this. The 360 Dev kits were out before the PS3's and final hardware for the 360 was available long before the PS3's. I think they didn't even have final hardware specs for the PS3 and were even considering dropping the Cell a year before PS3's release. Anyway, since all the developer tools were available before the PS3 was even in final hardware, they probably started developing it for the 360. I'm just guessing, but if it was built from the ground up on PS3 we would have it April 29th, 2009 instead of 2008.