Just before I left my previous job, my group was selected to be part of the Knowledge Network TAP. I only got to see a few demos, but it looks incredible. I did a bit of playing around in college with analyzing my inbox to see who I communicated with the most. KN takes it to another level by aggregating all that data from employees across the company. It also analyzes the content of the emails to determine your areas of expertise. Once all that is in place, anyone can say "I need a SharePoint expert" and the system will return SharePoint experts and the social path to reach them. Maybe a friend of a friend is the person you need to talk to so the friend in the middle can make the introduction. It's a great way to spread knowledge throughout a company with very little effort.

Channel9 has posted a video about the Knowledge Network. They do a lot better job of explaining it than I do.