Ask a bear: http://www.backpacker.com/ask_a_bear...ork/blogs/1889
I thought about it myself after encountering some black bears while hiking the Shenandoahs. I'm opting for pepper spray instead. Hope for the best and plan for the worst with that, but it's a good thing to have in the event of an encounter and one of the only things you can use in the event of a charge.
Rules in MA are funny - you can't ship regular mace/pepper spray for use on self defense, but you can order bear mace that sprays up to 35ft.