The thought of using an open source platform for a professional deployment within a demanding enterprise brings to mind a harrying array of possibilities: programmers unable to see the business issues and work as part of a team, a lack of documentation, hacked code and non-existent project management skills. Well, not anymore.

Social networking is not a new term, nor has it been widely applied to websites for more than a few years, yet it has clearly become one of the biggest buzz phrases of the Web 2.0 era. Nonetheless a great deal of confusion exists about just what makes a particular site an online social network. Of course, there's more than one answer, but most of us know this type of site when we see one, so clearly there are some common features that must be easy to recognize.

According to Wikipedia (in many ways an online social network in its own right):