While I think Hillary's statement about MLK is being overly parsed, I tend to side with Steve Benen and Andrew Sullivan as to its implications.
But I think there's even something more too it than this, and which compares more favorably with Obama.
And that is that LBJ accomplished much of what he did, including the signing of the Voting Rights Act, the year after his massive landslide victory, which swept overwhelming Democratic majorities into congress on his coat-tails. And while the death of JFK and the extremist campaign of Barry Goldwater helped contribute to that victory, the fact is that LBJ needed those large majorities in Congress to pass the Voting Rights Act and to pass Medicare and Medicaid, among other notable legislative achievements. Obama is campaigning with the recognition that large electoral change is necessary to accomplish significant political legislative and executive change. Hillary's campaign is based implicitly if not explicitly, on the idea that no such electoral change can or will occur and that political and policy change will happen only through the tough grit of experience.