Integration still limited to an in-app browser, but it works
In an effort to become more of a "one-stop shop" for all things restaurants and places, Foursquare is now integrating with GrubHub Seamless (formerly two services, now combined) for food delivery. If you're not familiar with the services of GrubHub Seamless, its a company that works as a middleman between restaurants and customers to deliver food. At no cost to the recipient, GrubHub Seamless will pick up your food at the restaurant and deliver it — hopefully from the restaurant's point-of-view increasing sales.
Now when you search Foursquare for a local restaurant in one of the hundreds of cities where GrubHub Seamless is available, you'll see a small "GH" or "S" icon under the contact details if the delivery service is available. Unfortunately right now that button simply loads up the mobile ordering site inside the app, but it does work. If you want to narrow down your search and have a better chance at finding a place that has delivery available, be sure to append your search with "delivery" — i.e. "Chinese food delivery."
You can grab the latest version of Foursquare from the Play Store link above.