The Sixth Annual International ICST Conference on Mobile and Ubiquitous Systems: Computing, Networking and Services (MobiQuitous 2009) will provide a forum for practitioners and researchers from diverse backgrounds to interact and exchange experiences about the design and implementation of mobile and ubiquitous systems. Areas addressed by the conference include systems, applications, social networks, middleware, networking, data management and services, all with special focus on mobility and ubiquitous computing.