Talked to the gallery, and the release party is on Thursday, but it is a private function, invitation-only. That's when Karl and/or Rick will be there, and I assume it will be after the gallery closes.
Edit: Found this picture of the invitation. Reception from 5-10 PM. RSVP Invitation only though. Interesting that it says it's a "CD/DVD" release.
http://img.ymlp10.com/magnumpr_UnderworldEmail_1.jpg