Ah, there are BTech players in eastern Massachusetts! The legends are true!
Anyway, Battleground Games in Abington seems to have a small following. I was there for a Warmachine tourney a couple weeks ago, and they had a goodly amount of Battletech stuff on display. According to their forum (
http://www.battlegroundgames.com/forum/), there's an AToW campaign and a Battletech map league running out of the store. They've also got a location in Plainville, but it doesn't seem to have any Battletech players.
Incidentally, anyone going to be bringing Battletech stuff to PAX East? I've got some 'mechs I mean to bring, but I've never actually played the game.