Monolith is working on a team-based downloadable FPS set in the Batman universe.
Warner Bros. Interactive Entertainment and DC Entertainment have announced Gotham City Impostors, and it's probably the first Batman game that won't let you play as Batman. The new downloadable title is a team-based FPS that casts players as soldiers in an ongoing urban war between impostors of Batman and impostors of the Joker. Players will appropriately join either team Bats or team Jokerz, and while nobody will actually BE Batman, they will be dressed as Batmen, often with comedic results.
The game otherwise appears to be a standard multiplayer shooter. Players will be able to customize their characters with weapons and costumes, and multiplayer modes include Team Deathmatch and Psychological Warfare, a version of capture the flag that replaces the flag with a battery that powers a brainwashing machine.
Gotham City Impostors is currently in development at Monolith Productions (F.E.A.R.) and will be available for download for the via PC, XBLA, and PSN. The concept art hints at a light-hearted game reminiscent of Brink or Team Fortress 2. I'd say that it seems like a completely preposterous way to use the Batman intellectual property, but setting things in the Batman universe will undoubtedly help the game sell.