I bought the collector's edition of Batman AA, and I got both Play as Joker and the Crime Alley DLC.  Crime Alley is a bit like the challenge maps, only you can select it from the Downloadable Content menu.  Joker can be selected on all Challenge maps and that's well and good, however I've noticed that he isn't selectable from the Crime Alley DLC, which has basically the same interface as the challenge map selection screen.  This doesn't seem good for the future of Batman DLC and I'm currently wondering if future DLC will support Joker as a selectable character.  I did a quick google and couldn't find if they'll be supporting Joker in future DLCs, do you guys know if they'll still support the Joker in future DLCs?

*spoiler game unlockable details*

Upon finishing the game you get to unlock Armored Batman in the challenge maps as well as in Crime Alley.  This is what got me thinking about the future of Joker.

Too early to know I guess.

I'm hoping for some Harley, Nightwing, Huntress, Poison Ivy, Tim Drake (Robin) action in the future, myself. But I guess they have to save something for the sequel.

Considering how well the game appears to be selling, I think the chances are good that there will be more DLC as the company can easily justify paying a team to work on it.  This could mean more extensive PSN DLC and some XBL DLC that was previously unannounced.