I have an embarassing admission to make, one that I imagine will get me ex-communicated from the plannersphere: I hate the word "influentials", I think that word-of-mouth/diffusion-of-influence theories are way oversimplified, and I didn't even bother finishing "The Tipping Point" when I bought it years ago. In my experience, the real world (especially the one that I was most immersed in when the book came out, the music world) is way too complex and random for most of these theories to be of much value (Seth Godin's "The Idea Virus" was another that I bought, but didn't get past something like page 30).
So, I've been happy to see a recent flurry of articles that challenge a lot of the assumptions about the role of "influentials". Because of social media, the overly simplified influencer-models are even less meaningful; ideas flow in many more directions, among previously disconnected networks. I have no idea what the model of the spread of ideas through a network might (eventually) look like, or even if that is possible, but I'm pretty sure it will bear little resemblance to the linear model that books like "The Tipping Point" map out.
Marketers probably want to cling tightly to the idea of "influentials" though, as it must still be comforting to think that they still have some control over what happens in the network, and how their ideas will spread: "Social Media? Sure, we can steer that in the direction we want, we'll just find the Influentials! Quick, roll out a viral and watch them swoon!"