Actor/stunt man Tim Storm talked to FanboyTheatre.com about his involvement in Spider-Man 3:
Well, yes, to reveal too much would mean certain death, but I will say the action in #3 will be even bigger than #2. From what I can tell,they are focusing more on Peter Parker than Spidey in this one. Dan Bradley and his crew are working hard already, coming up with some incredible stuff. I’m not sure yet what stunts or roles I will be playing, but I’m looking forward to it.
He also talked about Spider-Man 2 in the interview, which you can read in full at the link above.