Are you playing Foursquare? Are you “going out” with Gowalla? Are you looped in with Loopt? Location-based services are once again changing the face of social networking. Where relationships were once at the center of user experience, in the Golden Triangle of mobile, social, and real-time interaction, “places” take center stage and corresponding  activities and rewards become the cast and crew of the production. What started as a way to literally see and be seen, has now transformed into a…