Corporate clients in particular are rushing to embrace it. Ketchum cites the example of Dulux, for whom it created a 'Creative Panel' comprising some of the most fashionable names in design and style. Habitat head of design Tom Dixon and handbag guru Orla Kiely are some of the people it has grouped together in a forum which identifies trends and communicates them in the context of Dulux.
Last weekend's Sunday Times carried a double-page spread on its own think-tank, created with the help of YouGov, and chaired by John Humphrys, who epitomises the media influencer, and includes various captains of industry, trade unionism and the social world. Opinion Leader Research joint CEO Deborah Mattinson, who also presented at the Ketchum briefing, described the runaway success of the 'standing panel' of 'protagonists' they have created to test reactions to client issues across the board.
The art of turning all this into some kind of science was recently identified by Canadian journalist Malcolm Gladwell in his book The Tipping Point.
He described the stages leading to products or ideas reaching a crescendo of 'stickiness' so that they stick in the public's minds. In order to do this well, they need influential people to spread the word and simultaneously provide endorsement.
Gladwell's definition are people who are either 'mavens' or 'connectors'.
The people who make connections and shout from the rooftops, who bring people together, and let the ideas take root apparently effortlessly.
If ever there was a type that I'm reminded of, it's PROs. We want to promote, espouse, matchmake and generally make things happen for our clients and causes. It's just that we now know that you can do it in an efficient way.
Let's put it another way: throw off the chains of your press releases and embrace instead the new PR methodology of the opinion former.
Julia Hobsbawm is professor of public relations at the London College of Communication. Kate Nicholas is on maternity leave.