Foursquare Is Growing Quickly ? But Still Not Mainstream

Foursquare says it signed up its 6 millionth user last week, and that the location-based network has grown by more than 3,400 percent over the past year -- and the company's co-founder said it is worth $250 million. But it is still far from mainstream.

Samantha Morton Grace Park Jill Wagner Susie Castillo Fergie