@Cycloptichorn,
It depends upon the margin of victory. If I am not mistaken, Democrats have won easily here for a long time, including Teddy Kennedy, even with all of his exploits and problems. If this was in a state that was not solidly Democrat or liberal, then it would not be as huge in terms of how people are viewing Obama and the Democrats. Even if Coakley wins, if it is a very small razor thin margin, it is still troubling for Obama and Democrats.
Obviously I am hoping big time that Coakley loses in a rather definitive way, but I would take any kind of razor thin win by the Republican as a huge victory.