Both the Android version (since recently) and the iOS version (since today) of Foursquare now work with the real-time recommendations engine introduced this year by the developers behind the project. You'll find that the team behind this project have been waiting for some time to put it in the hands of Apple device users while the Android version has been flipped on since August 29th. This service allows recommendations to be pushed to your iPhone just as any other notification would - telling you what's good in the area depending on where you are, physically.
This update works with the recommendations of millions of suggestions from users, with "over 4 billion check-ins", according to Foursquare, allowing the features in Radar to expand to the real-time realm. Instead of needing to check on a list to roll with these recommendations, Foursquare sees where you are, what you like, and what's good in the area, and tells you about it proactively.
For those of you wondering how this always-on system is going to effect your smartphone's battery - it's about 0.7% of your battery an hour. That's what Foursquare suggests - we'll be testing that out soon, but for now, you'll rest easy knowing that, again according to Foursquare, that's "the equivalent of about a 20-minute game of Angry Birds over the course of a the whole day.
This update also brings on a "Nearby" button for "Right Now" recommendations including which of your friends are nearby and what's close by based on tips just as you'd get otherwise in real-time. This system also works with "Friends at a glance" via your friends most recent check-in, with additional details available with a tap.