Obama has won South Carolina's Democratic primary by a decisive margin. Clinton is in second, and Edwards came in third -- meeting threshold.
Also notably Clinton is slipping vis Obama in national polls, a trend likely to continue in the wake of South Carolina's demonstration that Obama can still win states in the Democratic primary and caucus process.
Leading up to Super Tuesday, there are really only two big pieces left to fall in place. What will observers make of Florida's delegateless primary on Tuesday? What will Edwards do and when?
After today, Edwards has clearly established that he can't win this race in any way other than through a brokered convention, and will be hard pressed to force one of those. He came in second place in the early Midwest primary (Iowa), and third place in the North (New Hampshire), the West (Nevada) and the South (South Carolina). Edwards has not bested Obama in a single primary so far, and also trails the other two Democratic candidates in national polls (I ignoring Mike Gravel for the moment -- he has yet to break 1% in a primary or caucus, and less than 0.5% of the funds raised of Clinton and Obama, and doesn't have a single pledged or superdelegate to his name).
Exit polls in South Carolina and some anecdotal evidence from Daily Kos polls both indicate that Edwards votes seems likely to break more for Clinton than for Obama, although Edwards supporters will not be monolithic. Edwards himself is believed to favor Obama over Clinton.
Sometime between now and Wednesday (after the Florida primary) would be a natural time for Edwards to withdraw from the race. Will he? If Edwards does withdraw prior to Super Tuesday, there will almost certainly not be a brokered Democratic primary. An Edwards withdrawal would also keep a very close Clinton-Obama race close, making even the latest primaries relevant. But, only one person really knows what he will do.