This document discusses research challenges and opportunities in mobile social networking. It outlines several areas of research including social graph fragmentation, community discovery, security analysis, and predicting trends. It then describes the state of the art in pervasive computing, social computing, context awareness, and personalization. The document introduces the SOCIETIES project, a 15.6M EU funded research initiative led by TSSG involving 16 partners. SOCIETIES aims to advance resource sharing, relationship discovery, community orchestration, and intelligent information usage across dynamic communities. The document concludes by discussing future research directions including merging pervasive computing with social networks and establishing federation across multiple social networking sites.