Since learning nowadays is conceptualized as a social system within communities of practice, the best way to learn is with others, in groups. In the past few years, there has been an increasing focus on social software applications as a result of the rapid development of new web technologies. Furthermore, mobile and ubiquitous technologies have provided capabilities for more sophisticated open social systems, where mobile knowledge sharing is the norm. In this paper, we explore the use of these concepts for learning and present a smart phone driven mobile Web Services architecture for collaborative learning.