I've been using MySpace, LinkedIn, and Facebook with various levels of enthusiasm and usefulness for the last year or so, and it's been interesting to see the shifting levels of usage among these tools. I'm going to reflect on how these social networking sites work for those of us who want to use them primarily as a way to maintain and build professional networks, not just personal networks.
Of course, the first observation is that social networks tend to blur the lines between the professional and the personal. Just how blurry this gets seems to vary somewhat depending upon the tool. That's one of the dimensions I'm going to consider.