Jack Nicholson did not play the Joker. Jack Nicholson played Jack Nicholson in goofy makeup. Those two movies don't exist, as far as I'm concerned.
Robin Williams is too old. Mark Hamill is just a fucking ridiculously stupid choice. And dubbing in his voice would be even worse. I mean, don't get me wrong, the guy RULES in the animated series, but.... has he even done a live action movie since Star Wars?
I think the casting of Heath Ledger is a clue to where Nolan is going with the character, a bit more straight, "plausibly impossible," like the first movie. The more I think about it, the better it gets. I cannot freakin' wait.
also, Clive Owen should be Harvey Dent/Two Face.