Top500 Supercomputers: Guess Who's Top?

The Top500 Supercomputer list is always fun, not least because it shows us where we will all be in a few years' time. There are all sorts of cuts of the main data, but the one you'll really be interested in is here; it shows that GNU/Linux ran a cool 75% of the Top500, and that a certain other operating system's share is so nugatory it's not even mentioned by name.