Etienne Wenger is one of the founding fathers of Social Learning Theory and the concept of “Practiced Communities”. People are learning together – every individual deals and engage in many different communities of practice. Here people negotiate and
Masters thesis on social software (e.g., blogs, wikis, social bookmarking services)...and how they support learning, knowledge management, and communities of practice.
Spannerworks, a search engine marketing company, has published a handy dandy guide to social media (PDF). The ebook covers the basics of blogs, podcasts, social networks, tagging, communities and Second Life.