After many rumors and much speculation, The New York Post has confirmed that Tobey Maguire is no longer attached to the fourth Spider-Man movie. The movie had been plagued with script and production issues for months, and now word is that all the setbacks and changes weren't working with Tobey's schedule.
Another rumor is that the powers that be want to focus on the high-school years of Peter Parker, so Tobey would be too old for that role. However, since Peter doesn't become Spider-Man until his senior year of high school, and the first movie already covered that, I have no idea what they could possibly come up with for this movie.
I agree with one blogger that they just need to sit on this for about 4 or 5 years, get a really good script going, wait for Tobey to be available again, and then reboot the franchise. It worked for Batman, why not Spider-Man?