Who owns the IP in a group blog?

Venkat digresses to ask that question after discussing the issue of whether Tyler Cowen should be kicked off the Island over at Volokh Conspiracy: Personally I hope we don't see a jettisoning in response to public outcry, as I believe proprietors of group blogs should determine membership outside of public reaction to posting.

I've got no problem with this Cowen guy myself, I kinda like his posts, but maybe they should boot him off for not being very responsive to emails.

Personally, I think it could be IP per permalink. Maybe that should be a new creative commons license.