Sony announced they had signed a deal with Epic Games to bring Unreal Tournament exclusively to the PS3 for 'this year'.
According to Sony, gamers will be able to port PC Unreal mods to the Playstation 3, and play them via a new multiplayer interface.
http://www.n4g.com/News-51215.aspx Incorrectly states that the 360 won't get the game at all. That news was never announced. This is a time-based exclusive.