According to this he is only considering a comeback.
''Mo Vaughn is considering a comeback. The former Mets first baseman missed all of last season with an arthritic left knee, but his agent said yesterday that Vaughn is feeling stronger and had asked him to see what opportunities might be available. "He's working out and doing better," Greg Genske said. "He's interested in what options there are." Genske said he had fielded calls from a few clubs and said Vaughn would be a good fit with an American League team, where he could be a designated hitter. The 36-year-old went on the disabled list for the Mets in May of 2003 and announced his retirement last January after doctors told him his knee would keep getting worse.''
http://www.nydailynews.com/sports/baseball...3p-217758c.html