What are you talking about, no Dave Grohl? He was the long-haired guy on the left side of the stage, mostly standing behind Skeeter and playing guitar in a very low-key manner. The only thing he didn't do was announce "I'm Dave Grohl," or try to trade on his celebrity in any way. He just looked happy to be among old friends.
Brian Baker came up on stage for the encore, too.
A couple of peeps actually had to leave in an ambulance as a result of stage divers, a pretty good reminder of why the Black Cat bans it. I hung back because of that, I didn't need to get kicked in the head by some tool trying to relive his youth (or some tool trying to enact his idea of what you do at punk shows).
my writeup here. Bottom line, really great show, and a mostly cool crowd despite the stage diving.
http://dcalex.blogspot.com/2009/12/still-screaming.html