By Ross Dawson
http://rossdawsonblog.com/weblog/archives/2011/02/it-is-the-structure-of-soci...
New York Times today examines the interesting question of Why Some Twitter Posts Catch On, and Some Don’t, starting from the fact that frivolous hashtags such as #worstpickuplines get far more attention than commentary on current affairs such as ‘Mubarak’, and going on to look at a range of research on influence.
The article quotes research which implies what I and a handful of others have been saying for quite a years now.
The structure of a social network — for example, whether it is made up of close friends and colleagues or of like-minded strangers who follow Lady Gaga — can have more influence than the size of a group, researchers say.
My Influence Landscape from 2009 shows the key elements of influence, including a section on ‘Influence Networks’ showing the elements of social network structure that drive the dissemination of influence.

As I commented in a 2007 post about other research on online influence,
What interests me in particular is how the structure of these influence networks will evolve – we are absolutely in a transition phase, and the way social opinion is formed will quickly change.
It is one thing to understand and dig into the structure of influence networks being far more important than individual influencers (see this commentary on Duncan Watts and the debate on whether “influentials” really matter).
Beyond that point the key topic becomes how this structure is changing.