While this game was unexpectedly announced for the Xbox 360 at last year's E3, Square Enix has returned again this year.
The company previously said that the Xbox 360 version of the game would start in development after the Japanese PS3 version was complete, but that was untrue today as Square Enix unveiled the game through some live gameplay at this year's Microsoft press conference. Have a look yourself thanks to GameTrailers.
And finally, Square Enix announced that Final Fantasy XIII would be arriving in North America for Xbox 360 somewhere in "Spring 2010."