Warning: Spoilers
Batman-On-Film reports the following information on the follow-up movie to Batman Begins:
"All the major characters from the first film aside from the villains are back," according to a studio insider. "Two additions to the cast of 'good guys:' Harvey Dent and Sarah Essen (an ATF agent)."
Also, "[The] Joker will be in this film, although he will be just one of several major villains" and "The Joker. I won't spoil things for you but those expecting an exact translation of [the Character] from the comics, in terms of costume, you will be disappointed. However, let may say that this Joker will be the 'The Joker;' the way character is written is very faithful to [how] he is in the comics and I can see why WB is not interested in actors like Crispin Glover or Johnny Depp."
And, "I won't reveal all the villains, but I'll leave a few hints that the avid comic fan should be able to decipher," the source says. “One will be an ambiguous mob boss with ties to the late Dr. Thomas Wayne. Another will be an industrial heir not unlike Bruce Wayne - in fact it could be said that he is a dark mirror of Bruce. Over the course of the story, he will be forced to present a new 'face.' And then we have a small, almost cameo type [appearance by a] villain who is considered a 'classic rogue' as a British arms dealer. It may sound a bit crowded, but it all fits together, makes sense, and works much like a comic story arc."
"As for the villains plot, the mob boss and the heir get involved with a major arms deal with the 'British Guy,' while Batman and his allies attempt to foil it," the source says. [As a result,] they uncover more of the corruption plaguing Gotham. Unfortunately for both sides, nobody knew there was a Joker in the deck who complicates matters."