Joe Klein, one of the most astute observers of everything political (and, increasingly, international) nailed the South Carolina primary in this post.

Make no mistake: What happened in South Carolina today was a moral reprimand delivered to Bill and Hillary Clinton by a united Democratic Party–but especially by the African-American segment of that party.
I chased the Clintons around South Carolina yesterday and the absence of black faces at their rallies was striking–eerie almost, the absence a palpable presence, as if the rooms were filled with ghosts. In Penn Center on St. Helena Island, which has been a historic nexus of the civil rights movement going back to the civil war–a place where Martin Luther King Jr would sometimes go to live in a rude cabin, and to write and think–Bill Clinton looked out on a lily-white crowd and he must have known what he was seeing: a silent, decorous protest against him by a segment of the Democratic Party that was always there for him in the past, the churchified African-American middle class, a group that represents the Democrats’ canary in the coal mine when it comes to injustice.
A mass, unspoken decision had been made that Bill and Hillary Clinton had behaved unjustly toward Barack Obama. It was the sort of decision that Bill Clinton might have tried to argue with, if it had come from the presss: “Hell, that Reagan thing…c’mon that’s the kind of thing Republicans do to us all the time. Barack’s gonna have to get used to it if he wants to play in the big leagues…” Except he had pulled the Reagan thing–trying to make it seem as if Obama had said that Reagan’s ideas were better ideas–with the wrong audience…and I don’t just mean black people, I mean an entire political party sick of games-playing.

And then there is this:

Obama struck precisely the right note in his victory speech, skewering the Clintons without naming them. And it seems to me that when he says that the election is contest between “the past and the future,” he is describing a situation that becomes truer every day, as the Clintons’ vestigial political virtuosity becomes more creaky and transparent, and just seems out-of-date and distasteful in a party that may want to turn the page on all that.
It may well be true that any Democrat is going to have to handle that sort of sewage in the general election, but I’ve now–belatedly!–figured out that the real audacity in Barack Obama’s campaign–far more than his positions on the issues, which almost seem an afterthought–is his outrageous belief that the entire country, not just Democrats, wants to see a straight up election; that the entire country is tired of the pestilence of tactical tricks that the Clintons learned from their co-dynasts, the Bushes. (The latest example being their sudden, sociopathic emphasis on the importance of the Florida primary, a contest all three candidates had agreed to eschew at the behest of the Democatic National Committee.)
It is a hell of a bet Obama has made. And nearly 40 years of political, uhm, experience tells me that it isn’t a very wise one…but I must also say that it is truly sad to see Bill and Hillary Clinton on the wrong side of it.