You may have already seen this video, but it is a great parable on trendy social movements and tipping points.
The audio description is what I found most interesting. The main lesson to walk away with is how crucial it was to easily mimic the dance. Were this a difficult dance, the originator would have been nothing more than an observed solo performer. Also the role of the first follower made it acceptable for a few more people to join. Once the first follower's friends join in, the tipping point is then reached at 1:15. From then on, people join in groups and the originator or "leader" is irrelevant as the movement has a life of his own. Only the music ending stops everyone from dancing, not the "leader."
Now take that template and apply it to al Qaeda in Iraq. What sort of impact would killing or capturing the leadership have today? This is precisely why the classic insurgency texts emphasized the need to destroy an insurgency at its onset. Otherwise it becomes an integrated part of a society for at least a generation if not longer. So how do we end the al Qaeda-styled movements? Find the music and turn it off.
The book "The Tipping Point" by Malcolm Gladwell is a great starting point for those interested in mapping the epidemic-like spread of societal trends through social networks.