The mudslinging has actually been quite tame so far in both parties. I'm not at all worried about any longterm splits.

The crowd at that South Carolina debate was very pro-Obama. They groaned whenever Clinton landed a punch on their champion. I think that's why some people thought Obama "won" that debate. The harsh exchanges that were replayed are about 6 minutes out of a 90 minute debate.

Obama went into the debate looking to pick a fight. (Which Hillary emphasized the next day.) Every negative interaction was inititiated by Obama. I think Clinton beat him on facts, but Obama looked a little better.

Obama accused the Clintons of lying about his opposition to the war. Clinton came back by acknowledging Obama's initial opposition, then named three ways he later equivocated. Hisses from the crowd at the dragon woman.

Obama said Clinton was a corporate lawyer sitting on the board of Wallmart while he was a poverty activist in Chicago. Hillary responds that she was working to bring healthcare for children in Arkansas while Obama was working for slum lord Rezko in Chicago. Loud groans and boos from the audience.

OK, here's the truth: neither of the accusations are that significant, but Obama's situation was more embarrassing. Rezko turns out to be quite the gangster, and he was courting Obama for many years. They have a string of small connections - contributions, job offers, Obama did some legal work for him, Rezko bought property next to Obama's mansion and transfered it to him.
Clinton a "corporate lawyer" for Wallmart? Ridiculous. As first lady of Arkansas, she was an honorary member of the board of directors briefly back in the 80's. Wallmart is the largest employer in Arkansas. And this was back before they became the notorious evil empire.

South Carolina is hopeless territory for the Clintons, Hillary is wise to have curtailed campaigning there. African-Americans have coalesced in racial solidarity, and even though the Clintons are their former champions, any friction they have with the Obama camp is being recast in a very ugly light. See her factual comment about the role of Lyndon Johnson in civil rights.