It would have been more interesting if the sizes had been based on some approximation of downloads/users/market share. The xkcd map, although a guess in some places, attempted to be grounded in something empirical.
Be honest -- how long did you stare at the map, trying to figure out where your country was, before you realized it was not based on real world geography?
I didn't, but then I'm familiar with the social network map the OP referenced so I kinda had a head start on knowing it wasn't real world based - http://xkcd.com/802/