There is a growing interest in the research and industry communities to examine the possible weaving of social elements into Web services-based applications. This interest is backed by the widespread adoption of Web 2.0 technologies and tools developed using various online means such as social networks and Blogs. Social Web services incorporate the result of this weaving and are concerned with establishing relationships with their peers like people do daily. This chapter reviews the recent developments in this new topic and identifies new research opportunities and directions that are still unexplored such as security, engineering, reputation, trust, and argumentation.