So Motorhead's pretty much confirmed as the "special guest" for Mayhem.
http://blogs.sfweekly.com/shookdown/...ter.php?page=2
Interviewer: "Do you foresee any Motörhead headlining dates in the U.S. to promote The World Is Ours, Vol. 1?"
Lemmy: "Well, we've got festivals in Europe in the summer and then we do the Mayhem Tour in July with Slipknot. But that'll be a short set, too, then I guess."