[noelchurchill]

I don't think anyone believes there is actually a bubble in diplomas. Obviously there aren't any DBS's (diploma backed securities), or diploma flipping schemes.

However you might be able to make the case that there is a bubble related to university costs, or the market for university grads. Tuition costs continue to rise while wages remain stagnant and jobless rates remain high. If this trend continues long enough, the demand for diplomas is bound to go down and universities will be forced to lower their costs.