Foursquare has released version 4.0 of its iPhone app with a new feature called Radar that informs users about stuff happening nearby.
Radar leverages new functionality available in Apple's iOS 5 SDK -- specifically "region monitoring." Once you opt in to Radar, Foursquare will send you push notifications when you're nearby places on the Foursquare lists that you've created and the lists that you follow, Alex Rainert, Foursquare head of product, tells Mashable. The application will also alert you when three or more friends are checked in at a location within walking distance.
Radar is a big step in the direction of Foursquare's vision, says Rainert. "This is something that we have been working on since Apple first released the SDK," he adds. "We're excited to see it in the wild … and learn from that."
Foursquare will add Radar to its other mobile applications in the months ahead. "Radar is core to what we want to do. It's important to us to have it available to all of our users," says Rainert