Facebook, Twitter, LinkedIn: How Should Managers Use Social Media?

How can CIOs make most excellent use of social media? Should they stick with the use of tools like Twitter and Facebook for private explanations, or may still they engage with a much wider community with a purpose to raise their personal brand and the notion of their business?

With the much talked about recent Facebook problems, we all have been reminded of the weaknesses of the heavy use of social media: in your opinion (please comment below) what is the good balance, what are the best practices that we should always keep in mind?