Penelope Trunk, a blogger, has written an eight part list of reasons not to escape the recession with graduate school. Among them are challenges to the value of doctorates, MBAs, law degrees, and medical school. They leave you overspecialized, dependent on future earnings to pay past debt, and perhaps with skills that are poorly matched to what the market demands.
While the list seems to include some reasonably good arguments and decent points, I think it misses the most important reason for considering grad school: namely, that having such a degree is something you personally value, and that people whose respect you wish to earn will value. Outside of highly practical fields like medicine and law, grad school is primarily an investment with low financial returns. Unless you anticipate high personal returns, it may be wiser to invest your time and money elsewhere.
Over on Free Exchange, there is a partial rebuttal.