The PlayStation 3 gets an exclusive character.
Eidos Interactive and Warner Bros. announced today that the Joker will be a playable character in the upcoming title Batman: Arkham Asylum – but only on the PlayStation 3. Joker will be available at the game's launch as a free downloadable item on the PlayStation Store. The press release notes that he will only be available for use in the Challenge Maps, so don't expect a massive single-player campaign associated with the legendary villain.

Arkham Asylum is already showing quite a bit of promise, sporting an intensely dark look and action-oriented gameplay. The Batman title is scheduled for a launch this coming June.

Edit: sorry didn't see the post with the same name, my bad.