Theory: S. E. is using the 360 in order to generate more money for FF Versus XIII
Think about it, we all know that Final Fantasy will sell extremely well on both platforms(might even pick it up on 360 XD), but has anyone noticed how Square Enix has just stopped all development for Versus in order to complete XIII?
To answer that question: Final Fantasy XIII and Versus are VERY expensive games to develop for. This is why they produced it for the 360 as well. Also, It will be released exclusively on PS3 in Japan because that will drive system sells up ENORMOUSLY. I dont believe that they will port this game to the 360 there because of the small userbase. So what Im trying to say is that they could not develop two AAA titles at once because the loss is wayyyy too high. Square Enix is not stabbing sony in the back, they actually want to develop for the PS3, its just that they need the money. Versus is my proof because it is coming exclusively to the PS3, instead of multiplatform.
BTW I think Final Fantasy Versus is better anyway.