Have examined packages like Foursquare and there are some fundamental problems with their use for marketing plays. Enterprises like Pepsi are trying to influence their design. Good idea if you believe lcoaation based social media are the future. In AdAge:
" ...Pepsi wants to get in on the ground floor of the next Foursquare. The marketer, which has been outspoken about its commitment to social media, crowdsourcing even its biggest marketing program through the Pepsi Refresh Project, is hooking up with a venture-capital firm to do just that ... " .