Last month, the Wall Street Journal reported an important effect of the 2008 presidential campaign: For the first time, traffic at left-leaning political Web sites overtook traffic at right-leaning competitors. The Drudge Report and Free Republic had the largest number of unique visitors in September 2007, but in September 2008, that honor went to the Huffington Post.

Political strategists have been analyzing the impact of the Internet on American political communication since at least the mid-1990s. When Hillary Clinton complained in 1998 about a "vast right-wing conspiracy," she was drawing on a 332-page study done by the 1995 Clinton White House alleging that a "right-wing conspiracy industry" was moving anti-Clinton material from Web sites in the United States to conservative papers in Britain and then back to mainstream U.S. print publications.

That 1995 report, and Clinton, too, were right on one point: The earliest significant impact of the Internet on political communication did come from the right.

Drudge was founded in 1994 and Free Republic in 1996. MoveOn was created in 1998 — precisely to respond to online anti-Clinton efforts — but it didn't gain real prominence until 2003, when George Soros invested. The other major left-leaning sites appeared after George W. Bush's election: Democratic Underground in 2001, Daily Kos in 2002 and Huffington Post not until 2005.

This pattern makes sense: The right, while in opposition, innovated with Internet tools; when the left in turn found itself out of power, it too developed new types of political communication.

But if Clinton was correct that the right dominated the Internet in the mid-90s, she wrongly attributed its success to conspiratorial methods. The word "conspiracy" fails to capture the remarkable power generated by Internet-based communication.

There are basically two kinds of influential political Web sites: sites that use a top-down hierarchy, whereby a central organization develops a message and disseminates it using social-networking technology, and sites that use a Wikipedia-type method, in which thousands of individual users contribute content and drive the message. This latter approach is exactly the opposite of conspiratorial.

The earliest and most powerful right-leaning Web site, Free Republic, used the non-hierarchical method. Free Republic developed innovative Internet architecture to build a sort of Wikipedia of citizenship, a do-it-yourself kit for spreading messages and connecting them with local, face-to-face activism. The site's discussion lists — which have global reach — are fed by participants and connected by those participants to a plethora of state message boards organizing real-time, boots-on-the-ground political action. The influence of the site reflects the power of self-organizing social phenomena, not a conspiracy.

Notably, the right has adopted the Wikipedia method more consistently than the left. MoveOn employs the top-down structure, as does the Huffington Post. Daily Kos blends the grass-roots and hierarchical methods. Democratic Underground copied Free Republic's grass-roots approach, but with less powerful architecture. One can't help wondering whether the right's more successful use of such self-organizing systems reflects the concrete impact of libertarian ideology.

But 2008 brought one major exception to the general pattern. Over the last two years, the Obama campaign built another "Wikipedia" of citizenship. It used its Web site to disseminate tools for grass-roots organizing and made its campaign infrastructure infinitely expandable as groups replicated over and over, learning from and copying one another. The campaign infrastructure became, to a significant degree, self-organizing. This explains its remarkable people power.

What will these successes mean for the future of our politics? In Federalist No. 10, James Madison argued that the geographical scope of the new country — even with just 13 states — would prevent the development of nationwide factions. But the Internet has eradicated barriers of geography, enabling much more effective factional organization than the Founders could have imagined. This is what Clinton was really marking when she complained about the "vast right-wing conspiracy."

Now, however, we are at a turning point. We've finally reached something of a left-right equilibrium in the dramatic restructuring of the public sphere that has been under way for the past decade. Against this background, on Nov. 4 the Obama campaign sent an e-mail to supporters from the president-elect signaling aspirations to convert the campaign's success with social networking technologies into a tool not merely for winning but for good governance.

Such a conversion would require transcending the factional patterns that currently define Internet-based political communication. It would demand a category shift: to remake the tools of factional organization as instruments of broad, cross-partisan and respectful public engagement.

Can this be done? If not, the Obama team's digital network could well become nothing more than an outsized, 21st-century version of a ward machine. If it can be done, it could restore a richer experience of citizenship.

Danielle Allen is the UPS Foundation Professor at the Institute for Advanced Study in Princeton, N.J.