Creating a Marauder's Map for muggles

With the latest Harry Potter movie opening yesterday, fellow GIS obsessed blog Very Spatial has an article on whether it is possible to truly create a "marauder's map". For those of you who are not versed in the ways of Hogwarts, the marauder's map is a map which shows the current location of every living thing in the Hogwart's castle. In our modern/real world the potential to know the location of people as they moved about their daily lives could be both scary and potentially cool and lucrative. While the article doesn't discuss ethical and or civil liberties issues surrounding such a map it does provide a nice discussion on whether or not such a map could be possible using today's technology.