What is Foursquare? Can you tell me..?

[angusisadj]

From what I know, it's just an app that adds location to your tweets, and you get medals rewarded for frequently visiting various locations. This website I visited described it as "a location service-based social network-come-game. What it does in effect is to tell you where your friends are and add a little fun to going out in the evening. It's like Google Lattitude meets a little bit of Facebook, a touch of Twitter, a dash of Qype and even a twist of World of Warcraft. And if that's not a cocktail for hopeless addiction, then we're not sure what is." Read the rest of the site (in my sources), it seems to explain it pretty well. I also put the official foursquare website in my sources.

If you were talking about the game, it's roughly a playground game where there is a large square divided into four equal squares. One person stands in each square and they bounce a ball to each square in no particular order trying to get each other 'out' by causing the other players to miss the ball... I don't know much a better way to describe it.