My arch-nemesis college runs it here in Texas (A&M) but it's a fantastic program. They've changed it some since I was in class, but it was pretty damn rigorous. To maintain membership in the MG society you have to have 12 hours of education every year, in addition to 40 volunteer hours.

I'm not an active member of the society currently, because I moved out of the county and driving for an hour to go to a class on tomatoes was a bit much. ;) I do a lot of online reading and of course, loads of hands-on training in my garden (and any neighbor that collars me on a good day.)