These latest rumors (not looking like the most iron clad of sources) concern the ladies in Gotham City. Supposedly, Charlize Theron is up for the role of Sarah Essen and Vera Farmiga (from The Departed and Up In The Air) and Kacie Thomas (from nothing that even sounds familiar) are being looked at for Julie Madison.
Sarah Essen (pictured) first appeared in the comics in Batman: Year One in 1987. She's a detective in the Gotham City PD and Jim Gordon's partner, but soon they develop a romantic relationship. Gordon was already married, so he breaks it off and Sarah accepts a transfer out of Gotham. Comics being what they are, they love to bring characters back, so eventually Gordon's marriage falls apart, Sarah comes back, and they ended up married. Then Gotham had an earthquake and the Joker killed her. I suspect most of that stuff would not happen in a movie, but if she is a character in The Dark Knight Rises, she'll be a cop and there will be some sexual tension with Gordon.
Julie Madison goes back to 1941, and is the first of Batman's major love interests. She's a socialite and aspiring actress who was engaged to Bruce Wayne for some time. She was involved in early stories of both The Monk and Clayface. She then basically disappeared for 60 years (though Elle MacPherson played her in a very small part in Batman & Robin (the George Clooney one)) before being resurrected by writer/artist Matt Wagner in Batman and the Monster Men and Batman and the Mad Monk.
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.