The title is being produced by Yoshinori Kitase (Final Fantasies 5-8 and 10, Chrono Trigger) and directed by Motomu Toriyama (FFX, X-2, and the Final Fantasy VII tech demo shown at last year's E3).
As far as we know, this is a PlayStation 3 exclusive. While no love was shown for Microsoft, the Xbox 360 does have three RPGs on the way from Japanese developer MistWalker, formed by Final Fantasy veteran Hironobu Sakaguchi.
Update: Gamespot reports that there are actually 3 different Final Fantasy XIII titles. The second title, featuring more spiky-haired madness, is also bound for PS3 and is directed by Advent Children's Tetsuya Nomura. The final game in the XIII trio is destined for mobile platforms.