A woman loses her phone, and recruits an army of volunteers to get it back. A dissatisfied airline passenger spawns a movement with her weblog. Citizens with camera-phones are more effective than photojournalists at documenting the London Transport bombings. The world's largest encyclopaedia is created by unmanaged participants. A handful of kids in Belarus create a political protest the state is powerless to stop. Everywhere you look, groups of people are coming together to share with one another, work together, or take some kind of public action.For the first time in history, we have tools that truly allow for this. In the same way the printing press amplified the individual mind and the telephone amplified two-way conversation, now a host of new tools, from instant messages and mobile phones to weblogs and wikis, amplify group communication. And because we are natively good at working in groups, this amplification of group effort will change more than business models: it will change society.