Mine alone and I'm saying it and posting it online first.
I believe that Joseph Gordon Levitt is replacing Heath Ledger as The Joker (as you see The Joker never "die" in the final parts of The Dark Knight)
The two actors look extremely alike and Levitt's acting prowess is immense. My guess is that he is going to be The Joker "incarnate."
Penquin WILL NOT be in this generation's Batman. Christopher Nolan has already said that these films are meant to be more dark, sinister, grimy, and realistic. Penquin is a joke.
However...The Riddler (Edward Nigma) is a great villain. But finding the actor that has the grace, intelligence, and pure insanity is hard. I vote for Paul Bettany.
Christopher Nolan isnt spilling the beans on anything relating to the plot of Batman 3 so we will just have to find out.