In 2010, Foursquare fans declared April 16 4sqDay (4/4^2). Its been two years since, and Foursquare has had two billion check-ins, and now has a user base of 20 million fans, says the company.
This year also the Foursquare day was celebrated with specials and giveaways across the world. Even government officials from Senator Wyden of Oregon to President Sarkozy of France tweeted about the day.
[Image Courtesy: Foursquare]