As usual, people read too much into the free practice times. We don't know fuel loads, we don't know what what testing strategy their doing, what parts they're evaluating (apart from the big changes, but that's probably only 50% of the changes)...
Hamilton is usually quick on Friday, and then gets lapped 15 times in the race. Brawn are usually overtaken by buses on Friday, but romp away in the races.
And some of the people predicting anything based on practice times really ought to know better. Especially when, in the past, they've said that practice times mean nothing...