The Dark Knight - "This town deserves a better class of criminal, and I'm gonna give it to them."
Well, I thought that was tremendous; a dark meditation on the effects of Batman's existence on his environment. The special effects are great, the direction and camera work are superb, but what carries the film is the acting, and the central commanding performance is Heath Ledger's Joker, magnetic, horrible, fascinating, makes what could have been a painfully silly storyline into a mesmerising carnival of terror. The other stars are great too; I thought at first that Christian Bale was a bit subdued as Batman, but I came around to him in the end. Everyone else has seen this by now, so I'll add that I was pretty impressed that they killed off a major character half way through - that really shows that all bets are off. Sorry, WALL-E, you were very cute but this will get my Hugo vote.
(I guess there is room for some debate as to whether or not Dark Knight is actually science fiction. But if it has made the shortlist, it is eligible for the Hugo, and it certainly feels sfnal to me.)