The final deal hasn't yet been reported, and I won't be able to do it, because I'm at the public library and I'm about to get kicked off. But so far, it sounds like the A's are getting Josh Reddick (and presumably something else) and the Red Sox are getting Bailey and Ryan Sweeney. I figured there would be interest in discussion, given that Bailey's value is at least somewhat comparable to that of Joel Hanrahan. I'm not a huge fan of Reddick's, honestly.
Update (by Vlad): It looks like the other two Boston prospects in the deal are first baseman Miles Head and right-handed starter Raul Alcantara. Both are risky but high-ceiling players from the low minors.