Foursquare announced on Wednesday that it has updated its client to version 4.0 with support for iOS 5. The update will provide users with access to a brand new “Radar” feature that takes advantage of iOS 5’s region monitoring capabilities to automatically alert you of destinations nearby that you might be interested in. If a friend or family member has checked in nearby, it will alert you that he or she is just around the corner. “When you’re in a new city, Radar can let you know about about cool places around you, even though you’ve never been before,” foursquare’s lead iPhone developer Anoop Ranganath told BGR. Foursquare for iPhone 4.0 is available in the iTunes App Store now and the update is free.