The Red Sox acquired minor league catcher Guillermo Quiroz from Seattle for cash considerations, the Mariners announced. The 30-year-old has experience in seven MLB seasons, and last appeared in the Major Leagues as a member of the 2010 Mariners.
Quiroz posted a .278/.362/.483 batting line in 347 plate appearances at Triple-A Tacoma in 2012 after signing as a minor league free agent last December. He also hit 15 home runs and represented the Rainiers at this year's Pacific Coast League All-Star Game.
BB Ref page
They've added him to the 40-man, but as of this morning he's not on the active roster. I'd assume he's just providing depth/insurance behind Salty & Lavarnway for the final weeks, since the Pawsox still need both catchers for the playoffs (Dan Butler, Mike Rivera) and neither is an MLB-caliber player anyway (Butler's likely headed for the Arizona Fall League at season's end).
What I'm unclear on is whether the Sox retain organizational rights to Quiroz for 2013, or if he's eligible for major or minor league free agency. I believe it's the latter, in which case the Sox shouldn't have had to give up anything beyond a $25 gift card at Starbucks for a month of his services.