The visualization definitely wasn't done in R. I'm guessing he used Gephi (see, for example, http://gephi.org/2010/map-geocoded-data-with-gephi/).
> As a sanity check, I plotted points at some of the latitude and longitude coordinates. To my relief, what I saw was roughly an outline of the world.
His plot doesn't "know" about the world - he is just drawing curves between points in a plane (lat. and long.). I haven't used R, but I am sure that would be possible.
But yes, it's probably possible to draw an uglier version of the visualization. (I know you can draw the individual points on the plane, so drawing lines between points is probably available as well, though I'm not so sure about the great circles part.)