Foursquare “Radar” Taps iOS 5 to Alert iPhone Users of Local ActivitiesFoursquare “Radar” Taps iOS 5 to Alert iPhone Users of Local Activities 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 pl
