For most schools, cost and debt are heavily related. These are the blue diamond schools on the chart: Haas, Booth, Kellogg, Tuck and Wharton. When you slap a linear trend on there you get an r^2 of .97 which is a pretty strong indication of a correlation. The trend says that debt is roughly equal to three times the required cost minus about $24k. So add in living expenses, some capitalized interest, a laptop and subtract some aid. The equation isn't particularly meaningful and the sample size is small. But HBS and Stanford are nowhere near that line.
The author of the article concluded that the reason that HBS and Stanford are different is that they give out way more need-based aid than their peers and that need, not merit, is their primary methodology in distributing funds.
For the graph above the debt numbers are from the Poets and Quants article and the required expenses are from Business Week's MBA program profiles. Sloan is not included since it appears that they didn't provide debt information to US News and thus weren't in the Poets and Quants article.
I found this pretty fascinating. The idea that a school's aid policies and budgets can make such a huge impact on a student's debt load is impressive. Of course I've made my decision on where to go, but if you were looking at business schools would you let this information sway where you applied or accepted?