Fast Company runs an article in which Duncan Watts, a network-theory scientist, puts to test the idea that trends are sparked by a handful of highly connected individuals, or the influentials, as they have become known after the bestsellers The Tipping Point and The Influentials.
"Watts believes [...] a trend's success depends not on the person who starts it, but on how susceptible the society is overall to the trend--not how persuasive the early adopter is, but whether everyone else is easily persuaded. And in fact, when Watts tweaked his model to increase everyone's odds of being infected, the number of trends skyrocketed.
If society is ready to embrace a trend, almost anyone can start one--and if it isn't, then almost no one can," Watts concludes. To succeed with a new product, it's less a matter of finding the perfect hipster to infect and more a matter of gauging the public's mood. Sure, there'll always be a first mover in a trend. But since she generally stumbles into that role by chance, she is, in Watts's terminology, an 'accidental Influential.'"
Watts has published several books on the subject, including Six Degrees: The Science of a Connected Age.
Update [Jan 27 '08]: Mike Arauz from Deep Focus responds.
My own beef with the theory of influentials is its implicit assertion, in my understanding of The Tipping Point, that if you have influence over a certain social network, this influence will have the same weight over the entire range of topics. I don't know if this Absolute Influence exists, and my own daily experiences offer nothing to support the idea: it is not a given that someone who is an apparel fashion trendsetter in one particular network will be have the same influence over the choice of others' plasma TVs, for example. Likewise, one's influence will also vary across different networks, which makes identifying and targeting The Influentials a much more complex task than it is suggested by the theory advocates.