I think there's a decent chance FFXIII goes to the 360, but I think it's more likely that it doesn't. I could be wrong, but I have a feeling FFXIII is too intimately tailored to the PS3 specs. It also hits the PS3 demographic perfectly so sales are gonna be huge on the PS3 despite a smaller install base. Also a ton of people would buy PS3s just for this game, so it may not be worth trying to port over a version to the 360 because it may not boost sales significantly enough to justify the change in development philosophy and extending the development time. But this is all speculation and is meaningless because what do I know.
P.S. Let's not make this a "360 can do everything a PS3 can do" thread. Please go to the "PS3 vs 360 graphics" thread if you wanna discuss that.
My Top 5:
Shadow of the Colossus, Metal Gear Solid 3, Shenmue, Skies of Arcadia, Chrono Trigger
My 2 nex-gen systems: PS3 
and Wii 
Prediction Aug '08: We see the PSP2 released fall '09. Graphically, it's basically the same as the current system. UMD drive ditched and replaced by 4-8gb on board flash memory. Other upgrades: 2nd analog nub, touchscreen, blutooth, motion sensor. Design: Flip-style or slider. Size: Think Iphone. Cost: $199. Will be profitable on day 1.
