Joe Trippi, Howard Dean's 2004 presidential campaign manager and Internet impresario, describes Super Tuesday II--the March 4 primaries in Texas, Ohio, Vermont, and Rhode Island--as the moment Barack Obama used social tech­nology to decisive effect. The day's largest hoard of dele­gates would be contested in Texas, where a strong showing would require exceptional discipline and voter-education efforts. In Texas, Democrats vote first at the polls and then, if they choose, again at caucuses after the polls close. The caucuses award one-third of the Democratic delegates.

Hillary Clinton's camp had about 20,000 volunteers at work in Texas. But in an e-mail, Trippi learned that 104,000 Texans had joined Obama's social-­networking site, www.my.barackobama.com, known as MyBO. MyBO and the main Obama site had already logged their share of achievements, particularly in helping rake in cash. The month before, the freshman senator from Illinois had set a record in American politics by garnering $55 million in donations in a single month. In Texas, MyBO also gave the Obama team the instant capacity to wage fully networked campaign warfare. After seeing the volunteer numbers, Trippi says, "I remember saying, 'Game, match--it's over.'"