This document discusses mobile social networks and location-based services. It defines mobile social networking as connecting with others using mobile phones. Key areas of focus are social networks extending to mobile apps and native mobile social apps using location data. The document reviews check-in services like Foursquare and Gowalla and how brands can engage users through special offers, rewards and incentives for checking in. Challenges discussed include fragmentation across many players and low app adoption rates. Sample brand campaigns using check-ins and rewards are provided.