Dave Grohl is hosting Chelsea Lately all week.
Elton John was a guest on the show  last night. And Dave and Elton shared the bombshell news that they played together on the new Queens Of The Stone Age album.

So, to recap, here is the current list of known guests:

Dave Grohl
Nick Oliveri
Mark Lanegan
Trent Reznor
Elton John
Brody Dalle
Jake Shears (Scissor Sisters)