As more and more people are owning Smartphones, such as the iPhone or any Android phone, and location based applications such as Foursquare gain more popularity, an interesting consequence results, which I like to call, the Long Tail of Real Life. In case you are not familiar with the principle of a Long Tail Economy, you should read Chris Andersons famous book on the very topic.
Essentially, a Long Tail Economy, which can be observed on the Web (e.g. at Amazon), can be described as the rise of the niches. For example, in a normal book store, only the most popular books are sold, as in a physical shop, there is limited space, and thus, niche products are only hardly to be found at a normal book retailer. The reason is simply, that only a few people buy those special interest books, whereas the large majority buys books, that are on the New York Times Bestseller list.
Amazon for example, has no retail shop. So every book they offer online is just another record in their extensive database. They are able to offer any book that is being published, because they are not restricted by physical shelf space. As having a special interest is not really unusual, we are buying those books on Amazon, as they are easy to find there. This is again resulting in serious sales numbers of large amounts of special interest books - many niche products that sell few numbers.
With handheld GPS devices, such as every modern Smartphone is, and with fun applications as Foursquare or others, this Long Tail behaviour also shifts to the real life in the sense of places. The more people you follow on Foursquare the more places you haven't known yet - even if its in the city you live in - you are likely to explore.
Also, as on Foursquare you have pretty much the same Follower-principle as on Twitter, meaning you are following people you haven't even met in real life, you are very likely to explore completely new places (as you perhaps know the majority of places your real friends visit). Thus, a simple Foursquare check-in at a nice little Cafe is a pretty mighty marketing tool, way better than, say, a poster in a train station near that little Cafe.
So a Foursquare check-in pretty much is like an oral recommendation, a word of mouth. As Foursquare is not only a location based service but also has gaming features, your are pretty likely to add a certain location to the map (say your little hidden Cafe), because you get points for it and because maybe, you are going to have another mayorship.
Of course you have to filter a the interesting places a little as many check-ins are at ones home, work or at train stations, but if Foursquare manages it to filter out the interesting places, such as shops, restaurants, clubs and cafes, the Long Tail of Real Life will be reality. So with this, the rise of the niches is also happening in Real Life, with the consequence of being able to explore many new places, in your own city.