Student debt: What's been driving college costs so high, anyway?

CSMonitor.com: Aaron Marks graduates this spring with a business degree from a good college, Carnegie Mellon University in Pittsburgh, and, unlike many of his classmates, a good job. He also has $191,000 in student loan debt. Mr. Marks's debt is extraordinarily high, but stories like his abound. Two-thirds of students graduate with debt, to the tune of $25,000, on average.