According to Empire Online things are already in the works for two Batman sequels: One involving the Joker and the second one Two-Face.
Normally I would call this sort of planning premature, but I really have little doubt that Batman Begins is going to both rake in the bucks and make fanboys around the world happy campers.
According to the article they won't be making the mistake of killing off villains, instead keeping them around to comprise Batman's rouges gallery as in the comics. They will also be connecting the transformation of Harvey Dent into Two-Face with the Joker.
Here's a bonus for you as well: New images from the upcoming film.
Good times if you're a Batman fan...