The world is an amazing treasure chest of cool things I never knew of. Luckily others find them, and so I can see them too. Beth Noveck points to Google, and writes about Google Map Mash-up.
Google map mash-up is, apparently, a combination of the geographical data from the map and the social data from other sources - perhaps your own? Google Maps Mania is a blog devoted to mash-ups, and you can find more about this in the New York Times article Beth Noveck refers to.
It's both fascinating and scary - the information we might get about what happens where, when, with whom.