Geolocation is used by loads of sites (for example when you go to a torrent site and you get them annoying pop-ups pretending to be a MSN messenger girl in your area looking to chat..
)
With VM it's easy for the geolocation to work as google has a complete list of UBR's and a site using googles geolocation always puts me in a town about 4 miles North West.. Where others not using google tend to put me about 8 miles North..