Yahoo has an article up dealing with speculation for Batman 3, including casting. Probably real early for stuff like this, but interesting to read either way.
As far as TDK - I agree with virtually everyone that it is an amazing movie, and I really enjoyed it. I don't like the comments (and it isn't a ton of them) where its like "this is how to make a comic book movie". I agree with that from the standpoint of respecting the source material, but I don't feel that all movies need to be as "dark and gritty" as BB and TDK are/were. This works for Batman, but there are several movies (Spidey 2, X2, Iron Man, etc.) that - to me - are very well done as well. Each character/universe has its own "feel", and not all of them are conducive to the super realistic, dark, and gritty style of Nolan's Batman world. Like I said, TDK was amazing though, and probably one of my favorite movies - so no complaints there. But, I don't mind a little "comic booky-ness" to some of the other characters' movies.