This is, as things work down here, actually the surface location of the geographical South Pole as of 1 January, 2011. The first day of each calendar year, the marker location is updated to its present position. The reason the marker apparently moves is because the ice sheet that constitutes the Antarctica Plateau is slowly moving at about 10 meters per year. As a result, the updated positions of the pole appear to march across the landscape in a line, but it is the landscape (or, icescape, if you prefer) that is actually moving.
The pole marker itself is actually from the 2010 crew with which I last wintered. We selected a design during the winter, and the following summer it was installed at the new/current geographic pole location on New Year’s Day. Similarly, on 1 January, 2012, we will update the pole location using the marker (kept secret from the public) selected by the 2011 winter crew. The machinist each winter is who actually fabricates the actual marker article.
"After I'm dead I'd rather have people ask why I have no monument than why I have one."