There is a continual growth in the use of social computing within a breadth of business domains; such as marketing, public engagement and innovation management. Software engineering research, like other similar disciplines, has recently started to harness the power of social computing throughout the various development phases; from requirements elicitation to validation and maintenance and for the various methods of development and structures of development teams. However, despite this increasing effort, we still lack a clear picture of the current status of this research. To address that lack of knowledge, we conduct a systematic mapping study on the utilisation of social computing for software engineering. This will inform researchers and practitioners about the current status and progress of the field including the areas of current focus and the geographical and chronological distribution of the research. We do the mapping across a diversity of dimensions including the activities of software engineering, the types of research, the characteristics of social computing and the demographic attributes of the published work. Our study results show a growing interest in the field, mainly in academia, and a general trend toward developing designated social computing platforms and utilising them in mainly four software engineering areas; management, coding, requirements engineering, and maintenance and enhancement.