When the Democrats met in Denver in 2008, we sat in skyboxes, high above the floor of Invesco Field, as Barack Obama accepted his party's nomination. While we were broadcasting for various radio and TV outlets, 80,000 Obama supporters were broadcasting as well cellphone by cellphone, Blackberry by Blackberry to their own networks of friends and family.

That moment marked a paradigm shift. We were part of the old, vertical system of distribution, where information was passed from the top down to a group of recipients "formerly known as the audience" (as Jay Rosen of the PressThink blog calls them).

The cellphone- and Blackberry-wielding Obamanians embodied a new horizontal system, in which information was transferred directly from peer to peer, person to person. They had made a key transition: from passive to active, from sitting in the audience to jumping onto the stage. They didn't have press cards or microphones or satellite trucks, and they didn't need them. All they needed was a connection and a cause.

We thought often of that moment as the spirit of revolution swept through the Middle East over the past two months. There is a direct line between Denver and Cairo, between the stadium where Obama was crowned and the square where Hosni Mubarak was crushed. Both events depended heavily on the new architecture of information, on the ability of people to communicate directly with one another, outside the filter of official news organizations or government censors.

But that new structure of communication has a second, even more important dimension. Yes, people inform one another and inspire one another. But the real revolution is inside their heads. The most profound change is not in how they talk to others but in how they think of themselves.

Jerrold Post, a professor of political psychology at George Washington University, says this is especially true for younger people who acquire "a sense of immediacy and being part of the process rather than just watching something happening." In an interview with National Journal, he added: "By interacting, getting a response, being out there, one feels not just (like) a distant individual who can have no impact in the system, but being part of the system that's really the profundity of this change."

Social media does not cause revolutions. They are caused by experience, by the festering frustrations and thwarted dreams of countless individuals. But social media allows those individuals to connect with one another, to encourage one another, to translate their isolated anxiety into collective action. As one of Steve's students put it, social media is not the spark of change; it is the oxygen that enables that spark to flare and spread.

The Obama campaign understood this dynamic well. The most common and most important word on their website was "you." Their brilliant insight was to utilize the interactive nature of social media by giving volunteers things to do donate money, organize rallies, walk precincts, distribute videos, register voters. Each act escalated their involvement in the campaign and gave them a greater stake in its success.

The Tea Party implemented the same principle, only more so. The Obama campaign had a recognized leader, a campaign headquarters and a fairly unified strategy. The Tea Party had none of that and still doesn't. It's a crowd-sourced movement generated from the bottom up.

"Liberals don't give nearly enough credit to the technological sophistication of the Tea Partiers," says blogger Nate Silver. "Thanks to (their) ability to find one another on blogs, Twitter, Facebook and so forth and to some extent the megaphone of Fox News these protests came together fairly spontaneously."

That's exactly what has been happening in countries like Egypt and Tunisia. Protestors found one another, and emboldened one another, through social media networks. As a result, they came to see themselves in a new way. They realized they could make history, and not just suffer through it. Wael Ghonim, the Google executive who emerged as a leader of the anti-government protests in Egypt, told "60 Minutes": "Without Facebook, without Twitter, without Google, without YouTube, this would have never happened."

The forces of entrenched power will not yield easily. Qaddafi stills shoots critics in Libya. The Communist Party still censors the Internet in China. The mullahs still round up dissidents in Iran. But from Denver to Cairo, the balance is shifting. The same forces that brought Obama and the Tea Party into office drove Mubarak out. The audience is growing restless. Crowd Power is growing stronger.