IMHO you should tough it out and try to hang on to it. In order to qualify for a short sale you need to show hardship (death, divorce, medical bills, etc.) and be insolvent (unable to pay your bills). Would you qualify?
I think a better approach would be to try to obtain a loan modification if you have cause.
If you are comfortable taking care of the payment in excess of what you collect in rent, you may want to just hold on to your home until the market turns around, otherwise it may be a good time to contact your bank to see what your options are.