Dave Grohl has appeared in an unlikely of places.. on the brand new Michael Jackson album due out Tuesday December 14th.

Dave Grohl plays drums on a track off Michael Jackson's new album. He appears on (I Can't Make It) Another Day.  Plus Lenny Kravtiz plays guitar on the song as well.  The album is simply entitled Michael.
By the way,  the Foo Fighters are looking to tour in 2011 to promote their new album.  Some dates are already lined up and are still being finalized. Dave Grohl states the Foo Fighters new album will be the heaviest album they have ever done.