This may be tricky as matches are being played over the vast South African landscape. Example Cape Town is about 1600 km from Johannesburg and almost 2000 km away from Durban. I suggest you check out the 2010 match schedule (link is on the blog) and decide where you are going to land. There are direct flights to Cape Town and Johannesburg. The next problem is going to be travelling domestically from match to match getting to and from the various cities.
A flight from Cape Town to Johannesburg takes about 2 hours and from Johannesburg to Durban 1 Hour. Driving takes almost 16 hours from Cape Town to Johannesburg!
Here is the link to South African Airports.
I will update this as soon as there is more clarity on World Cup Flights, currently all our airports are undergoing major renovations...but should be completed before the 2010 World Cup.