May 30th Arkham City will be dealing with Harley Quinn in two hours of new gameplay. The DLC will be available via PSN or XBL.

From the press release:

    Payback’s a bitch, especially when dealing with The Joker’s most psychotic sidekick, Harley Quinn. Harley is the new boss of Arkham City and is determined to make Batman pay for what he’s done to The Joker.

    Warner Bros. Interactive Entertainment and DC Entertainment bring to you today a new trailer and screenshots from Harley Quinn’s Revenge Pack, the final chapter of Batman: Arkham City saga that adds more than two hours of fresh single-player gameplay to the critically-acclaimed title from Rocksteady Studios. The Harley Quinn’s Revenge mission sends players back into Arkham City to face their final challenge as they interchange between playing as both Batman and Robin.

    Fans who already own the original edition of Batman: Arkham City will be able to download Harley Quinn’s Revenge Pack beginning May 30th on PlayStation®Network £7.99 and the Xbox LIVE® Marketplace for Xbox 360 (800 Microsoft Points). Newcomers to last year’s Dark Knight adventure will be able to pick up Batman: Arkham City Game of the Year Edition on September 7th in the UK, which includes all previous downloadable content (Catwoman Pack, Nightwing Bundle Pack, Robin Bundle Pack, Challenge Map Pack and Arkham City Skins Pack) plus Harley Quinn’s Revenge Pack.