Whether you are a buyer or a seller, short sales in Real Estate can be a daunting process. 

A "short sale" is when a lender(s) agree to accept less money than what is due to them. It is typically done in an attempt to prevent foreclosure and the costs associated with a foreclosure act.  This can include more than one lender if there is more than one mortgage on the home (i.e. equity, credit line, etc.). 

A lender will only accept a short sale if it makes financial sense to them.  The seller of the home (the borrower) must provide a documentation of hardship, proof of assets and other documents to the lender for consideration.  There could also be tax ramifications because the debt you owed is more than you paid back, the amount that was "short" may be taxable.  See The Mortgage Forgiveness Debt Relief Act of 2007 at http://www.irs.gov/individuals/article/0,,id=179414,00.html

If there is more than one lender, negotiations between all the participants can be time consuming requiring multiple levels of conditions and approvals. 

Also,  the buyer often has to wait for many weeks before they find out if their offer was accepted or not.  It is recommended that the buyer research the property title carefully to ensure there are no other liens on the property that would become the buyers responsibility once the property ownership transfers.   This could include back property taxes among other things.

Because of the complexity of these transactions, they have a high failure rate and very often do not close in time to help the seller avoid foreclosure.  Make sure to enlist the services of qualified professionals to help you through the ins and outs of this difficult real estate transaction.