David Brock is buzzing again: and the gadfly's main target is rush (and Bush, of course).(Media)

SUSIE TOMPKINS BUELL was very, very impressed with David Brock. A California businesswoman who co-founded the fashion giant Esprit and went on to become a major donor to Democratic causes, Buell was in Washington last fall attending a meeting of friends and supporters of Sen. Hillary Rodham Clinton when she met Brock, the self-described former "right-wing hit man." Buell listened as Brock, now a defector to "progressive" causes, presented plans for Media Matters for America, his new Internet-based project to monitor and criticize conservative media. In a short time, she was sold.…