Sorry I did not get back to you earlier. I can think of a couple of options so far:
1) Campus libraries: It seems it is easy for registered campus organizations to get access to meeting rooms. The problem is, although Berkeley Wikipedia club is a registered group, room reservation can only be done by a "signatory" for the group. The group mailing list itself is inactive - I wonder if anyone on this list (Kevin Gorman?) is a signatory.
3) I've written to my friend who works with the Compass Project, a student support group in the physical sciences, to see if they have any space that we can use - but I've yet to hear back from them.
Among these, the Berkeley Public Library looks like the safest bet. I'll let you know if I can think of anything else..