Proceedings of the Second ACM EuroSys Workshop on Social Network Systems, SNS 2009, Nuremberg, Germany, March 31, 2009

Humans have formed social networks since the dawn of history. Only in the past several years have these networks been represented within computers accessible from anywhere. This is a big change, with vast consequences not yet understood. For the computer systems researcher, social network systems present special challenges and opportunities. The trust network can be exploited to improve computer systems. New forms of workloads stress existing systems; databases, file systems, computer networks. This workshop provides a forum for researchers to exchange ideas on these topics. Last year, we noted that social network systems had been neglected by researchers. That is no longer so true. Since our first workshop, a number of other research venues have popped up. Last year, the majority of our submissions and accepted papers came from North America. This year, we were disappointed to not receive a single submission from that continent. This may be related to poor economic conditions and decreased travel budgets. Fortunately, we did receive thirteen submissions, and from those accepted eight into the workshop. We are pleased with the quality of the final papers and the strength and depth of the program. The papers are organized into three sessions; personalized search, social graph structure, and privacy and security. Discussion during the workshop ranged across the merits of decentralized versus centralized architectures and designing for privacy. Despite a tight reviewing schedule, all submissions received at least four reviews from program committee members. Several papers were shepherded to improve their presentation and clarity.