hey gents... I would actually have to respectfully disagree and here is my experience. I have lived in milton ma for years now (about 9 miles south of downtown boston) and driven a BMW for 10 years. On both my e46 M3 and now my 335 i have never run a front plate and that is approximately 10 years of commuting into Boston daily. Even when i have been pulled over, probably about 4 or 5 times the only thing that has ever happen is the cop saying "get your front plate on".
In short I have never received a ticket or a fine for not running a front plate. Maybe I am just lucky, but just wanted to share my experience.