Wow. I wasn't aware of that. I assume that the New Bedford/Fall River voters were responsible for that, because I can't imagine Newton/Brookline going for Brown.
http://www.nytimes.com/interactive/2010/01/19/us/politics/massachusetts-election-map.html
Here is the map. You can click anywhere on it to see what towns Brown won in. I was very surprised that the western portion of Mass did not vote Brown. I seem to be in an extremely portion of our state. Yay for our towns!