Foursquare is celebrating its third-annual 4sqDay in impressive fashion.
Whenever users check in on the service today, they'll be awarded the 2012 4sqDay badge, which is accompanied with a message announcing that the startup now has 20 million users worldwide, and has hit a whopping 2 billion check-ins since it was founded in 2009.
"In 2010, Foursquare fans declared April 16 4sqDay (4/4^2 - nerds after our own heart!)," the message that accompanies the badge reads. "Two years and two billion check-ins later, you're still why we get out of bed each day. … Read more