The college football season thus far has been rife with upsets, most notably with Stanford beating USC a couple of weeks ago (Go Cardinal!). Although some may prefer that top-ranked schools stay that way in the BCS, for others, the upsets are welcome and fun to watch.
One commentator on National Public Radio offered up the following possibility for why the college football playing field seems to be much more even than usual: many colleges have cut their rosters to 85 players, since they've been limited (by the need to comply with Title IX and other issues affecting the athletic budget) to offering fewer athletic scholarships to football players. The result is a trickle-down of athletic talent to schools that would not be able to recruit elite players if the rosters at the top-ranked schools were larger. The effect of having more elite players spread out among a greater number of schools is that the chance for an upset of a traditional powerhouse team becomes greater.
I wouldn't attribute the slew of upsets solely to the smaller rosters, but it's certainly something to consider.