They are available in new england, just not terribly popular. They'll likely have a lot more available in the coming months as they are taking on some production capacity of the red hook brewery in Portsmouth NH. Their 312 is a pretty good summer wheat beer should you get the opportunity to enjoy one.
I have been drinking GI in Chicago since their beginning, and have found all of their recipes safe and a little, well safe. Their Matilda and Bourbon County are truly exciting and very age-able. Try those they aren't cheap but very very good. Good rating..