Glenn Reynolds quotes John Scalzi's comments on Michael Moore's Best Documentary nomination for Bowling for Columbine
Bowling for Columbine will win Best Documentary, because it's the only documentary most of the Academy is aware of, and because Mike Moore loathes George Bush and so does Hollywood.
I don't think John's first point applies. The voting rules for Best Documentary state that people can only vote if they have seen every nominated film in the cinema. (Normally they do this by attending official academy screenings in LA and NY. The academy keeps records of who attends the screenings). This means that the people who vote will have heard of all five films. It is often the case that an obscure film has won over a commercially successful film in this category, whereas it is much less likely in categories where voters do not have to prove they have seen the nominated films. (The same rule applies for the Best Foreign film category, which also leads to obscure films often winning).
Another issue with the documentary feature is that films about the Holocaust very frequently win. This is obviously a very worthy subject to make documentaries about, but there is a definite pattern in the academy's choices. This year we have as a nominee Malcolm Clarke's Prisoner of Paradise , about a Jewish film director who was forced to make a pro-Nazi propaganda film in a German concentration camp. Judging by the academy's past record of picking documentary oscar winners, this stands a good chance of winning. If this can prevent Michael Moore from winning, I will be delighted.
So I suppose it all comes down to two factors: how much Hollywood hates George Bush, and how much Hollywood resents Michael Moore's obnoxiousness. I think people who don't want Moore to win need to go out of their way to publicise Moore's awful behaviour towards the theatre staff in London, actually. The out of work actors who make up much of the academy are hardly going to be impressed by it.