Mendeley is a relatively new reference manager and research tool, which has done much to introduce a social network element to reference management. It was in the educational/tech press earlier in the year when Elsevier (the publishing giant) bought the company for a reported £45-£60 million (see the report in Wired for example).
A colleague has been offering introductions to this, and you can see his slides below.
Or here is another set of slides from a librarian in Singapore:
