Contra Jon Cohn, I don't see how Ted Kennedy's endorsement will actually help Barack Obama win votes. Sure, it's a dramatic rebuke to the Clintons, and the media loves this sort of stuff, but as far as actual electoral traction goes, it's difficult to see how this endorsement will, say, put a dent in Hillary's 37% lead in Massachusetts, the state where a Kennedy endorsement would most make a difference (it's doubtful that Patrick "I have never worked a f*&^ing day in my life" Kennedy will help Obama much in Rhode Island). Whatever the Kennedys' virtues, endorsements do not play the sort of role in convincing voters that the media portrays.
And even if the Kennedy endorsements mean something, it's not a sure bet that they're even a help. Jon Keller of Boston's CBS affiliate has more on why the Kennedy charm just ain't what it used to be, particularly in their own backyard.