I've always sworn by SmarTraveler living in Boston. They used to have a great phone in service with recorded traffic updates, 617-374-1234, but the state recently cut it to save money in favor of an automated line that you can reach by calling 511. The new 511 one just isn't very useful since it tells you the speed traffic is flowing at, not the time it will take, and it only tells you exit #s, not exit names and landmarks that everyone knows.

In any event, SmarTraveler also lists info about construction and events occurring that will affect traffic in town.