Is South Carolina not at least partially in the North Carolina and Virginia Georgia media markets? I'd think they'd be seeing quite a few ads already, no? I could be completely wrong on this.
But I'll concede I've been hoping Obama will leave South Carolina be. I think Obama could flip it if he campaigned hard enough.
The problem is that South Carolina has a polarized electorate with only a small middle and more Republicans than Democrats. Obama needs to get at a minimum 60% of the independents and more like two-thirds to have a realistic shot. However, as others have noted, a good deal of the State overlaps with neighboring media markets. The Charlotte, Greenville-Spartanburg-Asheville, Aiken-Augusta, and Savannah markets all have considerable coverage. Charlotte and GSA are getting heavy media buys as part of the North Carolina campaign, but they are in fairly Republican areas of the State. Georgia is a better target than South Carolina, but I haven't seen any evidence of campaigning in the CSRA (Central Savannah River Area) market and probably not in Savannah either. Once Georgia is in play, the Midlands, Charleston, and Pee Dee markets are all small enough that it might be worth spending money there if Obama can afford to go on offense rather than defense, especially the Pee Dee if he thinks he can help the Democrats snag the newly created 7th District there.