I would say this one ranks even lower in likelihood than the Lester-for-Myers rumor, mainly because Bailey's value is so low it's incomprehensible that the team would pawn him off.
Last year, the Red Sox acquired Bailey along with Ryan Sweeney for Josh Reddick. Reddick blew up, smacking 32 homers and 29 doubles as an unlikely key cog on an unlikely successful run by the A's. Bailey was hurt, and then pretty bad, compiling a 7+ ERA over 15 innings.
Now, we all know the team subscribes to the theory that a sunk cost is a sunk cost, but there's also public perception. The Red Sox are not going to send off Bailey for a middling prospect or two when the year before they gave up a 30-home run hitter for him. And no one's going to trade anything more than a middling prospect, so look forward to Bailey as the closer at the start of 2013.
At the deadline, assuming we're well out of contention? Then you might have a different story.