The only explanation I can think of to why Casey Affleck is nominated for best supporting actor is that they didn't want both Casey Affleck and Brad Pitt competing with each other in the best actor category. Similar thing had happen before with "Pulp Fiction" when Samuel L. Jackson was nominated for best supporting actor and John Travolta for best actor when both of the actors had same about of screen time. Arguably, Samuel L. Jackson was the better actor than John Travolta in the movie.

Javier Bardem should not win. Tom Wilkonson made Michael Clayton credible along with Clooney. He was the character in the movie that made Clooney's "Clayton" seem so redeemable.

This is a no brainer. Javier Bardem, lock stock and barrel deserves Best Supporting Actor. His performance as Chigur(I hope I pronounced that right) is terrific.

The common choice across the board seems to be Javier Bardem, and I understand why he should and will win. Granting the typical lifetime achievement award to Hal Holbrook may not occur, as they skipped over Peter O'Toole last year, so the nomination may be their nod to him. Tom Wilkinson is one of the finest actors of the bunch, but he won't win for the simple fact that his role doesn't diverge enough from his norm, and I can understand that. As mentioned, Hoffman won for Capote. Despite the reasons why the OSCARS would not choose those actors, I would argue that Casey Affleck and Javier Bardem are just much stronger contenders. Affleck is obviously the underdog in the battle - he's young and the Jesse James film did not garner much public attention. The last time we saw Bardem he was a sweet quadriplegic in The Sea Inside, so seeing him as an unnerving killer with a bad haircut and speaking very good English no less was a shock. While I love rooting for the underdog, and while Affleck's performance as Robert Ford deserves a win (especially since, as Peter mentioned, it really is more of a shared lead role, and he outdoes Pitt), my vote goes to Bardem as well.