Most of the overtaking to lead races takes place in the pit-lane. This is where the faster cars such as the RedBull and BrawnGP cars will be able to blow Hamilton away.
If overtaking only happened on the track, then Hamilton would be in a very good position.
For this reason, providing we have a dry race, with no freak incidents/accidents/breakdowns, I can't see how Hamilton can be on the podium.
I'm shocked as to just how fast Trulli can be in qualifying, yet in the race, he is as slow as a snail. And before anyone talks about having a heavy fuel load - he is getting pole position with heavy fuel loads, yet his race never seems to be anything like his qualifying pace. Puzzling.