Antarctica is the southernmost continent on the planet. By definition of the Antarctic Treaty, it includes all land south of -60 degrees latitude. This does not include various subantarctic islands which can be considered belonging to Antarctica geographically.
Antarctica poses many problems for OpenStreetMap due to its uniqueness (mostly covered in ice for instance), geographical position around the South Pole (which leads to many problems in usual map projections) and emptiness (not many mappers around).
Data import and tagging
New data for the Antarctic coastline has been imported replacing the previous data which has been quite bad. See Antarctica/Import_2013 for details on this import and Antarctica/Tagging for the Antarctica specific tagging established with this import. Also, Antarctic Digital Database Data has been imported offering additional and more detailed information.
Creating an Antarctica map
Due to its position around the South Pole, the usual map projections show Antarctica rather distorted. On the typical tiled web maps the area below about 85° South (and above 85° North) is not shown at all. See Creating a map for some tips how to create specialized Antarctica maps. An example for usage of such a special map projection is the slippy map at http://polar.openstreetmap.de.