bdude writes "People already know social network for sharing picture, related to friends and blog. An article on BBC talk about social network base on geolocalisation. For you could meet your friends (or friends of your friends) by suprise in the street of New York by SMS notification and look on the map where there are. Kakiloc push it to the limit by offering live location reporting. Have a look to it. Some people may fear a little bit more the "big brother that watching you""