An online goof suggests that players may be able to increase Arkham City's cat content.
A listing on the GameStop website may have inadvertently revealed the existence of Catwoman DLC for Arkham City. According to the listing, BradyGames' limited edition guide to Arkham City contains details to "all four" episodes of Catwoman content.
We've known that Catwoman was playable in Arkham City for some time, but this is the first mention of additional content for her. It's not hard to imagine what it might be; Catwoman doesn't just disappear when you're playing as Batman, and there's all kinds of things she could be getting up to in Arkham City. Of course, that's assuming that it's story-based, which is what the word "episodes" implies. It could just be new challenge maps - it certainly wouldn't be the first time that downloadable content has let you play as one of Batman's rogues gallery in an Arkham game.
Obviously, this is all just speculation until Rocksteady and/or Warner Bros. confirms or denies it. We've reached out to them both, and will update if and when we hear anything back.
Batman: Arkham City comes out for PC, PS3, and Xbox 360 on October 18th.