In the post-Crash world, I think screeners are going to dictate a winner more than ever before (screeners + internet hype = Academy momentum and then likely box office).

Slumdog Millionaire wasn't a huge hit before it starting picking up SERIOUS steam (IIRC), and Crash did okay but not until it picked up a lot of buzz with the genius campaign of waiting until it was on DVD to send it out to voters (something IB did this year...reducing cost yet still getting as much voting traction).

I think it's a 3 way race, and Avatar is leading right now.