The season is young & I would still put my $ on Hamilton
But I have to say that after getting up a 5am to watch the qually and seeing how well Brawn GP done with an excellent car and 2 seasoned drivers it wouldn't surprise me at all if Brawn GP was in the running for the constructors title, and possible the drivers title too.
As Brawn said in an interview earlier today Honda gave up last season trying to get anywhere and concentrated on the 09 car so it has been in development for a lot longer than other manufacturers.