Last week, Foursquare added a fascinating new feature called Radar to its iPhone app. Rather than having to check-in to see what’s happening at a venue, Radar uses the technology introduced in iOS 5 to provide you with notifications when you are close to a location that might be of interest to you.

If you’re situated close to a place on your To-Do list, not too far away from a place where a bunch of your friends have recently checked-in or if you’re close to a place that’s on a list you follow, Foursquare now sends you a notification to let you know. A significant side effect of this means that you may no longer have to check-in manually.

At the Web 2.0 Summit in San Francisco, Foursquare CEO Dennis Crowley said that the location-based service is becoming more passive and that could lead to greater adoption of Foursquare. According to CNET, Crowley says, “[Radar] is what we’ve been trying to build since grad school.” He admits that it’s a challenge to convert people who are tentatively interested in the service into becoming active users, but the passive nature of Radar has the potential to make it easier to do just that.

Looking ahead, Foursquare is focusing on its recommendation engine (which was launched in March), merchant tools and Radar, because that’s the direction in which the company wants to take the app. That certainly indicates that check-ins may be killed off — tips, photos and other information related to venues are starting to be delivered to you rather than you having to look for them, so removing check-ins in favor of Radar is a logical move that Foursquare might make down the road. However, the game mechanics (badges, mayorships, etc) are likely to stay. Crowley says, “I’m a big believer in using game mechanics to push people to do things in real life.”

Foursquare is facing stiff competition from the likes of Facebook (which killed off Facebook Places in August in favor of integrating more location-based features throughout the social network) and Google — which has its own location-based service, Google Places, and has baked location sharing into Google+. However, Crowley contends that the Facebook challenge in particular is a motivating, rather than debilitating, factor for Foursquare.

“It’s one of the more challenging things to deal with [but] we have a narrow focus on building things that help people experience the real world,” he says. “How we are able to survive the Facebook onslaught is a big motivating thing for the company.”

Crowley also revealed his belief that Foursquare will still be an independent company in 12 months (the $50 million funding round that Foursquare closed in June should certainly keep things running smoothly for the foreseeable future), but his main focus is on building a superior company and product.

Foursquare hit 10 million users in June and hit 1 billion total check-ins last month. More than 3 million check-ins take place every day, while more than 500,000 businesses are using the merchant platform. It’s clear that Foursquare has a large number of active users, but perhaps Radar will help the location-based service to become more popular by attracting even more users and a higher level of engagement.