During their media event, Sony announced that while 'Unreal Tournament 3' will be multi-platform, it will be a "timed exclusive" for the PS3. Meaning that if you want to get in the action this year, you'll only be about to do it on Sony's concole. It won't be out for the Xbox 360 until 2008.
Another small surprise was that any mods people have or create for the PC version of the game will be transferable to the PS3 version as well. But the PC version doesn't come out until 2008 either. So...yeah.