I never expected that an article at CNN.com would surprise me, but this one did. It discusses how people were shocked to discover that, after a successful short sale or judicial sale, the lender pursued them for the remainder of their debt.
This should come as no shock to anyone familiar with the industry and with the foreclosure process. However, if you're not familiar with those things, it can be a bit surprising. When an individual buys a home with a mortgage, there are two documents that are executed. One, the Note, contains a promise to pay back a debt. The other, the mortgage, ties that debt to a specific piece of property that can be taken to satisfy the debt.
So, don't be surprised. If a lender releases the mortgage, you may still be liable for the remainder of your obligation under the note.
This actually happens in situations related to when a Deed In Lieu of Foreclosure is done improperly.