Southeast Michigan Lojban Group - A group of about half a dozen Lojban enthusiasts meet at Matt Arnold's house in Redford, Michigan about every two weeks (except when college is in session, because so many of them are undergrads, grad students, or teachers). Regular attendees include Bruce Webber, TheRomp, Shaun Klein, Neil Eppstein, and Alex Martini. The group has been going in one form or another since March 2005.
A Lojban group started at Grinnell College in Iowa, in October 2006.
Jay Kominek is interested in starting one at the University of Colorado, let him know if you're in the area.
Robin Lee Powell (me) used to teach a class in the Silicon Valley area, in Northern California. I'd be willing to do so again if enough people were interested. I know two people here that would attend, but I'd be interested in other jbopre joining.
Anagram is interested in informally gathering for a workshop of beginners in the Bakersfield, California area. Try contacting him via irc.freenode.net. My registered nick is Anagram, you may leave me a memo via memoserv.
Arnt Richard Johansen will teach anyone in Trondheim, NO who is interested. Contact him at arj ATT nvg dot org.
There has been talk of some of us Southern Californian jbopre getting together in Pomona monthly. More info at SoCalLojbanists.