For 5 years I lived in Boston (Jamaica Plain), and there is definitely a bit of a learning curve to getting into the rythm of Boston driving. I grew up in NYC so it wasnt that far off, but my Girlfriend, who grew up on the Cape never really seemed to get the hang of it.
There is definitely a lot of non-verbal cooperation that goes on in Boston traffic. After awhile you get really good at reading the vehicle language (like body language but with cars) of your fellow motorists and you know whos going to cut you off, or who can be cut off.

After moving to the Cape, my ingrained defensive/offensive Boston driving was way too aggressive for the local year round Cape Codder's (not the tourists. Theyre all insane...). So I've relaxed my technique and lightened up a bit.
And I learned to give the horn a rest. Nobody down here seems to use 'em...

With the summer months coming up, I may have to take my Boston driving skills out of the closet though, and give them an airing. As soon as school gets out and the vacationers show up, its every man for himself.