This article in the same edition of Harvard Business Review is quite interesting too:Why did we ever go into HR?:
In particular;
"HR is poised to become the Facebook of the modern corporation. Many knowledge-management initiatives have failed because employees weren’t inspired to use them. Yet the rise of social-networking sites points to a widespread desire to connect with others who share your goals and interests. HR is uniquely positioned to connect people—and therefore knowledge, expertise, and mentorship possibilities—across an organization. For instance, leadership-development program alumni can participate in annual reunions hosted by a firm’s top brass and serve as advisers to current program students. Follow-ups such as these—and the programs themselves—help build networks of people from disparate parts of the organization and with vastly different areas of expertise."
I think the examples are a bit week, but I agree with the sentiment, the general importance of social networking, and HR's key role in making this happen.