Wikipedia: "The small world phenomenon (also known as the small world effect) is the hypothesis that everyone in the world can be reached through a short chain of social acquaintances. The concept gave rise to the famous phrase six degrees of separation after a 1967 small world experiment by social psychologist Stanley Milgram which suggested that two random US citizens were connected by an average of a chain of six acquaintances."
Update:
Check out David Bradley's article on Six Degrees of Separation from ScienceBase and We’re Far Removed From Proof of ‘Six Degrees’ Theory from the Wall Street Journal.
Personal observation from Sean:
I have done work in this area [social network analysis] and have found that many of the "hubs" in organizations are so not because of titles, status or even friendliness but the result of physical location. For example, in a 300 person call center, the people with the most inbound links / edges tend to be those in the higher traffic areas.
Interestingly enough, most of the connections tend to cluster geographically where the average person relies on those in their immediate vicinity for the majority of information sharing: what we call "six feet of separation." Getting up to ask a question of someone outside of that immediate area presupposes the usually "good enough" answers available from their proximity peers may not be sufficient.
