A Gamestop description of the Batman: Arkham City official strategy guide, spotted by OXM , strongly suggest that Arkham City will be getting some bonus Catwoman DLC after launch.
"Bonus Catwoman's Walkthrough: Get complete coverage of Catwoman's DLC content! All 4 episodes are revealed!" reveals the blurb. Whoops.
Catwoman will be playable for a small percentage of the main game, but will still get her own set of gadgets and a quick, agile fighting style.
The other bullet point uncovers twelve side missions. "A number of major characters are revealed by finding and completing these tasks." New characters Penguin , Mr Freeze , Two Face and Solomon Grundy have all been shown so far. Who else would you like to see making an appearance in Arkham City?