Coakley ran a poor campaign, didn't communicate well, and didn't put much effort into it until the end. Brown campaigned like he meant it, found a message that resonated with voters, took advantage of some anti-Dem backlash, and ran with it. I really think that this is case here in MA, and that it's not a huge resonating anti-Obama referendum.
Good campaigns beat crappy campaigns, every time, that's the lesson here. Don't take any race for granted, unless you're Ted Kennedy running against
Jack E. Robinson.
In the end, big whoop. A very average, indistinguished state Senator will probably manage an average, indistinguished few years in the Senate until the end of Kennedy's term. I think Alan Khazei (a Dem primary candidate for you out-of-staters) would have kicked Brown's ass in this race and I hope he runs again.