I live right near Boston.
The penalty is if you have an ounce or less it will be deemed personal use as long as it's not in baggies separated by the gram for example (obvious distribution) you will get a fine if it's not bagged up (100-200$ I believe but someone correct me if I'm wrong) and will not get arrested.
Anything more than an ounce then that's another story and being taken in is a possibility if the cop is a real asshole but most 5-0 around here just take your stuff and smoke it themselves, good ol massachusetts 8)
What I'm currently wondering is about the good spice-a-like products and if caught smoking that is a crime? I mean it doesn't even look/smell like cannabis but with my luck they would think its Salvia and give me a hard time...
The JWH series is still unscheduled but clearly states "not for sale in USA", not to get off topic I was just curious if there is an answer to this but I don't think anyone knows as of yet. However, the germany bust revealed an HU chemical in a blend (scheduled) and that concerns me, funny thing is that it wasn't in all blends even of the same brand, odd stuff..