It looks like Batman: Arkham City will be getting some new DLC starring Joker's deranged, doting lover, Harley Quinn. Eurogamer have spotted a number of Playstation 3 trophies on PS3Trophies hinting at new missions starring the sassy assassin. One of the achievements also mentions that Robin will be playable.
The Boy Wonder made his first appearance of the series in a brief cameo during Arkham City's single player campaign. Forget the camp green hot pants of ye olde comic book Robin, in Arkham City he has a hood, which makes him five times broodier. More importantly, he has a big stick, which was great fun to use in Robin's challenge map DLC pack. It'll be interesting to see Quinn's fighting style in action. Expect lots of somersaults.
Warner Brothers haven't confirmed or denied the existence of the DLC pack yet, but there are a few details in the full achievement list below.