taken from Wikipedia:

"Reformation and new album (2007–present)
On April 19, 2007, the band's website posted a news article stating that a new Slipknot album "will surface in 2008." Jordison explained in a recent Kerrang! Magazine interview that this album would be the heaviest they've ever made, but still containing some experimental sounds, and recording shall commence in January 2008.[22] On April 19, 2007 Jordison stated that he would be drumming for Korn in the summer of 2007."