More and more, I'm seeing tweets about people becoming mayors of coffee shops in my Twitter stream. They're playing Foursquare on their phones, which pushes their "checkins" or location disclosures out to their Twitter followers. Foursquare is part cellphone social-mapping game, part Yelp (another way to find food, drink, or friends using your phone's geolocation technology). "A large number of … [Read more...] about Foursquare & other geolocation apps: For young adults, not kids