Dave Grohl was recently photographed in the studio with Josh Homme from Queens of the Stone Age (and Eagles of Death Metal) and with Jesse Hughes (also from EODM).
Jesse posted the picture on his Instagram, but deleted it later, luckily somebody saved it before that happened, so we can see it, too.
The fact that he posted it, then deleted it means something GOOD is happening, in my opinion... otherwise, why take it down? So whose record are they working on? Queens of The Stone age have confirmed they're working on a new album, so that's my best educated guess. Time will tell, I suppose.