Rocksteady Studio's community manager, Sarah Wellock, tweeted that the latest DLC for Batman: Arkham City, Harley Quinn's Revenge, would be coming April 30th. After checking for the update last week, we were let down when nothing appeared. It turns out the first announcement generated so much buzz, that the follow-up correcting the date to May 29th went largely unnoticed.
May 29th also being the release date for the Batman: Arkham City Game of the Year Edition, it makes more sense. Until then, here is the promo image for Harley Quinn's Revenge (is anyone else not liking this logo at all?) and the trailer for the GOTY edition.