I am an active member of a number of different social networking sites and my friends on these sites fall into one of three categories: 1) People who are actually my friends; we talk, email, IM, have lunch together; 2) People I sort of know, used to know better, or know mostly through a tiny online avatar; and 3) People I actively ignore.

By far the largest of these categories is #2 and these are probably the people to whom I am LEAST “connected” (those in category #3 I know well enough to have a reason for ignoring them).

But because of online networks like Facebook and LinkedIn, there is an immediacy to our friendship that could not have existed just a few years ago. In essence, the degrees of separation in our relationship have been removed.

Nicholas Christakis from the Harvard Business Review offered this from his research:

“Yet although a person may be connected to other people by six degrees of separation, he or she is influenced only by those up to three degrees away.”

He goes on to explain that not only is the window of influence is tightened around closest friends, it gets progressively weaker with each degree: “We have found that a person is 15% likelier to be happy if his or her friends are happy, 10% likelier if the friends’ friends are happy, and 6% likelier if the friends of those friends’ friends are happy.”

What does this mean for marketing and business? On its face, it seems remarkably obvious: my actual friends in category #1 are going to have a greater influence over my life than those in #2 and #3.

This effect has spurred businesses to take advantage of the immediacy of online friendship to develop communities around their products. The problem for marketers is that while technology has minimized the degree of separation, it is only in rare cases that businesses have been able to replicate a feelling of community strong enough to engender trust and influence. So most companies just end up in category 3.