6) Toy Story 3. I had somehow missed the first two Toy Story films, and based on this I don't feel especially deprived. The animation is cute but the plot risible. Woody's barely reciprocated loyalty to Andy is rather pathetic, and the rest of the characterisation is wafer-thin. You more or less know what will happen in the film from the first five minutes, and I found it difficult to keep up my interest.
5) Harry Potter and the Deathly Hallows, Part 1. There are some good moments in this - notably the legend of the Three Brothers, told in animation about three quarters of the way through - and Emma Watson and Daniel Radcliffe are still very watchable, as are many of their older costars. But it's awfully slow and yet also disjointed. Shame that they didn't gut the book (which is also too long) and just make a single film of the good bits.
4) How to Train Your Dragon. Another animated film, but one with actual plot and humour, as the geek among the Viking warrior kids discovers that intelligence and compassion can be better than brawn and bashing things when dealing with awful threats like dragons and adolescence. It's not exactly profound, but the script is witty and the animation excellent.
3) No Award. I mean, seriously, folks, it would be embarrassing for any of the above to win.
2) Scott Pilgrim vs The World. I found it pretty easy to rank the lower three, but wavered between my top two. In the end, though I greatly enjoyed this, I am putting it second. It's a lovely film, but I was sorry about the inevitable screen truncation of Scott and Ramona's relationship from the series of graphic novels and concentration on action sequences (of which my favourite, the library fight between Knives and Ramona, was also axed). The film also seemed a bit more racially dodgy than the original. Still very enjoyable though.
1) Inception. In forty years' time, when my grandchildren (or yours) ask me how I voted in this year's Hugos, I think this is the only defensible choice. Admittedly I found it rather hard to follow, due to being in pain and on various drugs while watching it in several installments, but that was true when I watched all the others as well, so in fact not a great excuse. It looks and sounds utterly fantastic, and is clearly paying homage to Philip K. Dick while bringing in various other sexual and social paranoias, in the ultimate example of someone's personal relationships interfering with their career. I wasn't totally sure about Ellen Page (either her character or her performance), but maybe my appreciation would have been greater under normal circumstances. In any case, no work of art is perfect, and I can happily give this my top vote.
Previous Hugo category write-ups: Best Short Story, Best Dramatic Presentation - Short Form.