South Sudan has become the world's newest nation. I've just had a look at the major online mapping websites and it seems that none of them have yet added South Sudan.
However Ogle Earth has created a KML file that shows the outline of the new country. The map includes the town of Abyei which, pending a referendum, will officially belong to both South Sudan and Sudan.
You can view Ogle Earth's KML file on Google Maps here.