As you’ve probably heard by now, Catwoman’s playable in Batman: Arkham City. Naturally, just her presence in the game means you’ll end up having to rescue her at some point. If you’re curious as to how that goes, you can see it for yourself:
Catwoman isn’t the only character Two-Face interacts with. At E3, we also discovered a tape of conversations between him and Hugo Strange. You can listen to those conversations here.