Foursquare gets 15 more citites
The cities added are all in the USA and Canada, and the full list runs: Baltimore, Cleveland, Indianapolis, Kansas City, Milwaukee, New Orleans, Omaha, Pittsburgh, Raleigh-Durham, Richmond, Salt Lake City, San Antonio, St. Louis, Montreal and Toronto.
Foursquare challenges its users to "check in" at locations using GPS, describing itself as 50% friend-finder, 30% social cityguide and 20% nightlife game. The idea is that you discover new things while being aware of where your friends are. It comes as an app for the iPhone and Android platforms and a mobile site for other smartphones.