ANALYSIS: Protesters took to the streets in past conflicts; today their presence may be strongest online. In May, saddened that she had failed to stop the war in Iraq that took her son's life and made her the face of opposition, Cindy Sheehan tearfully quit the anti-war movement. She had concluded that her son Casey, a 24-year-old Army specialist killed in an April 2004 battle in Baghdad, had "died for nothing." "Casey died for a country which cares more about who will be the next 'American Idol' than how many people will be killed in the next few months," Sheehan...