For them, and anyone else who doesn't read Instapundit, Michael Barone summarizes the concept nicely:
Higher education bubble poised to burstHere's video of Glenn talking about the subject: The Higher Education Bubble, and What Comes Next.
Imagine that you have a product whose price tag for decades rises faster than inflation. But people keep buying it because they're told that it will make them wealthier in the long run. Then suddenly they find it doesn't. Prices fall sharply, bankruptcies ensue, great institutions disappear.
Sound like the housing market? Yes, but it also sounds like what Glenn Reynolds, creator of instapundit.com, writing in The Examiner, has called "the higher education bubble."
Government-subsidized loans have injected money into higher education, as they did into housing, causing prices to balloon. But at some point people figure out they're not getting their money's worth, and the bubble bursts.