Foursquare And The Last 10 Million
blog.4sqday.com
Foursquare just passed 20 million users. It was at 15 million in December, and 10 million last June — 10 months for 10 million users. Instagram just added 10 million in 10 days, making it twice as big as Foursquare in roughly half the time (3 years to 18 months).