I see this as a logical extension of all the existing location-based social networking stuff out there (Foursquare, Gowalla, Facebook Places, and even Yelp). S

I see this as a logical extension of all the existing location-based social networking stuff out there (Foursquare, Gowalla, Facebook Places, and even Yelp). Since I'm sure all of these guys are already working on extending their apps to be more flexible in this area, you'd be doomed before you started.