Buried in the news about Alberto Falcone was a little item that Juno Temple was believed to be up for a part in The Dark Knight Rises. Blastr.com believes it to be a female Robin, presumably Carrie Kelly from The Dark Knight Returns. Christopher Nolan and Christian Bale have both expressed an aversion to the entire concept of Robin in their movies, so I'm quite confident Juno Temple will not be playing any kind or Robin.
Since original Juno Temple blurb used the phrase "a street-smart Gotham girl," a much more likely part from the comics would be Holly Robinson. She's a long-time friend of Catwoman who first appeared in Batman: Year One as a teenage runaway/prostitute under the protection of Selina Kyle who actually stabs Bruce Wayne in the leg. Much later, Holly would go on to briefly assume the identity of Catwoman. You can read a lot more about Holly at wikipedia.
After The Scarecrow, Ra's Al Ghul, The Joker, and Two-Face, who should be Batman's next enemy in the Batman Begins/The Dark Knight series? Well, as of now we know that Tom Hardy will play Bane and Anne Hathaway will play Catwoman.
Check out the master list for all the villains covered. I've pretty much run out by now. Obviously, there are more Batman villains, but not any of significance that I know of. As of February 2009, no one is confirmed as a villain. Not the Johnny Depp Riddler, not Phillip Seymour Hoffman Penguin, nobody.