Joaquin Phoenix is the best American actor we have right now, hands down. He can do anything. I'm looking forward to seeing Walk The Line.
He did win an Oscar a few years ago, for The Color of Money. He should have won for The Verdict. He was fantastic in that. I think he's a great actor. I think the reason he didn't do as well as he could have in Cat on a Hot Tin Roof was that the homosexual relationship hinted at in the play was very watered down for the movie, for obvious reasons, so Newman had to hedge his performance.
Joaquin Phoenix is a great actor too. I agree with you. But Heath Ledger was better in Brokeback Mountain than Phoenix was in Walk the Line, IMO. But this is why the Oscars is very silly on some level. Comparing great performances in very different projects is pretty goofy.