Short sale has nothing to do with the length of time a property is on the market. It refers to the fact that the mortgage company is willing to accept a payoff, less than the actual amount owed. This is a common situation for those in hardship, or those over-mtged. If the mortgage company is willing to negotiate, it is unlikely that a property will be foreclosed upon. Short sale talk is an indication that everyone is willing, or at least, will consider working out problems!
If you are considering purchasing a home under a short sale--be prepared to wait--it is a lengthy process.