Here Comes Everybody: the power of organizing without organizations, by Clay Shirky. Penguin Press, 2008.
This book should be required reading for all adults. Kids already know this stuff.
Beginning with an elaborate re-telling of a saga involving a lost cell phone, Shirky illustrates how people connected by cell phone, twitter, and other social networking tools form ad hoc groups that can have an influence far beyond the power of even well-organized and estblished groups.
On-the-scene reporting of news events (like the recent plane crash in the Hudson river) puts a new face on journalism. Invitations to be part of a flash mob give people a way to organize meetings in touchy circumstances below the news and police radars.
I believe one of the strong messages we should bring from this book is that, in order to maintain dignity and power, organizations NEED to know about these on-the-fly ways of organizing and devise ways to use them, too, in pursuit of their own goals.