Foursquare has been updated to version 7.0, with a new design and more awareness of what's around you. Things like the feed, location details, and even the sidebar have all be retooled.
The check-in feed has been redesigned with a more compact timeline of friend activity. Split up into Worldwide and Nearby, the feed is no longer under a map. Instead, pull down on your feed to reveal a rotating selection of tips from Foursquare, as well as the Worldwide/Nearby switch, and a button to take you to a map of your friends' locations. Pull down even further to refresh your feed.
The app will now deliver push notifications based on your location, alerting you to things like what one of your friends says about a restaurant you're in, or good deals to take advantage of while shopping. Foursquare also tries to present you with new things every time you open the app, so you'll see more of what's nearby.
The update to Foursquare is available now, and requires iOS 7.