You want the real full title of the game? DISSIDIA 012 [duodecim] Final Fantasy. Our database groans just from the thought of it, so let's go for {Dissidia Duodecim: Final Fantasy} for now. Square Enix have announced that they will bring out the PSP action game in Japan on March 3, without mentioning a release date for the US or EU. There will also be a bundle with the game and the console called Chaos&Cosmos Limited, but we're still waiting on information of what that pack will actually contain.
Update: According to Italian distributor Halifax, Dissidia Duodecim is slated for release in the EU in spring 2011. That's nice to know!
If you're interested in the title, you can always check out this gameplay footage we captured off-screen during Tokyo Game Show.