Variety is reporting three new additions to the Dark Knight Rises cast: Daniel Sunjata (pictured) best known for Rescue Me, Diego Klattenoff best known from the short-lived NBC series Mercy, and Burn Gorman from Torchwood. Read Variety's article if you're interested in incredibly vague descriptions of who the cops might be, but there's not much there.
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.