According to Ken Rosenthal of FOXSports.com, the Twins have placed Joe Mauer on revocable waivers.
It's common practice in August for teams to place their players on waivers, so this isn't necessarily significant. If Mauer is claimed, the Twins could pursue a trade, assign his remaining contract to the claiming team or simply pull him back from waivers. Rosenthal speculates that the Red Sox could be a potential fit for Mauer at some point, but it would still be a surprise if he's moved. Mauer still has six years and $138 million left on his contract with Minnesota.