When I was a kid Four square was a game we played with a ball and four squares. Now Foursquare is a way for people to let their friends — and weirdos—know exactly where they are at any point in the day.
They “check in” via their cell phones and leave details about what they are doing there. In theory it’s supposed to be sort of a guide to a location. For example, you could check in at Sally’s Ice Cream shop and tell the world that the Mocha Pecan ice cream is to die for. Then others in the area might check out Sally’s ice cream as well.
Here is a video teaching you how Foursquare works.
While I can see the attraction of location-based technology for consenting adults, the mother in me is TOTALLY creeped out by the idea of teenage and college-age girls broadcasting their locations!!
Foursquare isn’t the only location-based service. Twitter offers TwitterWhere and apparently Facebook Mobile also lets you