via the Top500 blog
The Top500.org blog has set up a Google map showing where the Top 100 largest supercomputers on the list are housed. Interesting to note that they are nearly all above the equator.
Map is out of date, however, as it doesn’t show the XT3 at the ERDC MSRC (currently #26).
Update: the map isn’t actually out of date, they just put Vicksburg in Michigan somewhere.