A recent artice on Fastweb.com confirmed what many have believed all along. Going to a top school is not an immediate ticket to the job of your dream. According to this article, corporations prefer hiring graduates from state schools over many Ivy leagues.
Part of this is for reasons stated in the article: graduates of Harvard and the like tend to go on to grad school or work at Wall Street, while graduates of state schools go into the workforce. Therefore, those students are better prepared for the workforce. But I think there may be other issues at work as well.
First off, the two stongest jobs that you can get in terms of job security are teacher and nurse. Neither of these pay a lot, but require quite a bit of schooling. Therefore, when choosing an undergrad school, students looking to go into that profession are going to consider price as a big issue.
Also, despite what the American dream tells us, most students at Ivy league schools come from well-off families. They have some form of fallback. Many students at state schools may have to get a job because otherwise, they will have no place to live.
Finally, state school graduates assume that the school on their diploma will not be enough to land themselves a good-paying job, so they compensate through activities and leadership roles. Graduates of Ivy league schools may assume that good grades from a prestigious school are enough and just don't try as hard when looking for a job or building their resume.