As much as I dislike it, I see Ferrari doing very well in the first race at least. They reduced their wheelbase slightly, and despite the fact that Maclaren increased it to similar levels, Ferrari has more experience on where exactly to dial in the wheelbase and Albert Park is a good track for the longer wheelbased cars.
In the middle, I see Williams and Renault gaining ground on the Sauber team. Sauber I think will pull out ahead with their budget and development capacity, but they seem to be having teething problems. Williams I think could qualify very well, as long as they keep their cars understeering (for Rosberg). Toyota is odd, they'll either be a the bottom of this group, or the very top if they learnt their lesson on what worked for the last year. Red Bull. no significant developments, hopefully refinement, though I don't see them going that far this year (unless they find race pace). Rosso have great driving talent, but what'll happen with their old chassi we'll see, though after testing is over they'll be less confident.
Red Bull/Toro Rosso
The bottom rung, anything could happen. Honda has a terrible car (I'm waiting till 2009 before the Ross investment becomes noticable) and aren't going anywhere. Super Aguri will only be able to run a 2006 car, with little or no development because of their financial situation. Force India has Mike Gascoyne, who doesn't care about the handling of a car at all (ask Christiano da Matta), and they'll be bought out sooner or later anyways.