As with every other coherent idea I have heard from the OWS-types, it sounds great...as long as you do not analyze any deeper than their soundbites.
This is being portrayed as "power to the people", but OWS has no power. They can't force the banks to sell debt on their terms, all they can do is bid against debt collection companies for the debt. By paying the banks for this bad debt, OWS is rewarding the banks for making loans to people who can't pay them back, giving the banks more reasons to continue this behavior.
When you settle a debt for less than 100% of face value, my understanding is that the unpaid difference counts as taxable income (I am not a tax expert!). By forgiving someone debt, OWS MIGHT be making them liable for the taxes in that "income". Or OWS could try to withhold the data from the IRS, resulting in hilarity for all.
I would think the lucky few who are rewarded with a forgiven debt would simply be encouraged to borrow more. Why should they learn anything except "my actions have no consequences, everything will somehow work itself out"?
Student loans: The upswing in student loan debt came as a result of the government guaranteeing student loans a few years ago. The banks will give student loans to just about anyone who asks, for any amount within reason, because they are not taking a risk. The banks are not going to sell recent student loan debt for less than 100% face value, they can get it from the government anyway.
I hope OWS spends every penny they have on this project. Better this than buying camping gear and stinking up our parks.