Foursquare. A place for brands.
Brands are a part of our everyday lives. That's now a given, mostly due to the power of "traditional" advertising via mass media over the past 75 years or so. What most companies are now striving for (or need to be) is a way to make that integration more natural…more authentic. With that in mind, I think Foursquare (and it's contemporaries like Gowalla and Facebook Places) is something to pay attention to. Because it's geolocation based permission marketing.