From our friends at NAR:
Fannie Mae and Freddie Mac, the Government Sponsored Enterprises (GSEs) announced changes to their Standard Short Sale and HAFA guidelines to improve transparency and marketing of listed properties that will require GSE approval.
Starting Aug.1, 2013, any property being considered for short sale approval must be listed on the multiple listing service (MLS) for five consecutive days, including one weekend, prior to Fannie Mae or Freddie Mac approving a short sale offer. Both GSEs will require that printed copies of the property's MLS listings in the geographic area in which the property is located.
For more information, see Fannie Mae's June 19th servicing announcement at the following link HERE (PDF).