Meanwhile, Facebook, the worlds most popular mobile social site, has recently updated its privacy policy in a way that allows for locationbased features, and is rumored to be working on its own Foursquare killer.

Some think once Facebook gets going on geolocation, there will be no stopping it, and no hope for currently popular mobile geoapps like Foursquare and Gowalla the former having just gotten involved with perhaps its most mainstream effort yet in a deal with cable network Bravo.The popularity of the apps has attracted notice from other Web startups that rely on local advertising, says BusinessWeeks Aaron Ricadela. Foursquare boasts nearly 300,000 users, and Gowalla has more than 100,000. On Jan.