But in the hours and days that followed, something very different happened.  "That switched. A lot of people we hadn't seen for months, or years, started showing up. An attack [on some sites by Anonymous] happened that night," he said. "It just angered them, not frightened them."  Housh was speaking at South by Southwest Interactive on Tuesday, the annual festival in Austin devoted to Web and digital culture. He appeared on a panel with the director of a documentary about Anonymous, and two people who spoke (one via Web chat) wearing the movement's trademark "Guy Fawkes mask."  The masks, patterned after the one worn by the shadowy anti-hero from the comic book and movie "V for Vendetta," gave an almost surreal air to the panel at a conference where black-framed glasses are a more common fashion accessory.  As a crowd of about 200 watched, "Anonymous 9000" spoke on a big screen, his mask and white gloves lending theatrics even as he talked soberly about the inner workings of a movement that has alternately inspired, intimidated and baffled the Web.  "I was kind of mesmerized by what was going on," said Brian Knappenberger, who directed "We Are Legion: The Story of the Hacktivists." "This is an attempt to define that culture."  In recent years, Anonymous has been involved in some of the most high-profile cyberattacks on the Web -- hobbling the websites of governments and businesses, hacking into sites to reveal private data and, along the way, getting dubbed cyberterrorists by authorities in the United States and elsewhere.  Who is Anonymous? Everyone and no one  The group claims no leaders or power structure and doesn't require any sort of membership. That, some members say, is a blessing and a curse.
When it's revealed that a prominent member of a clandestine movement has been giving information to the FBI for months, you'd think it would intimidate others in the group into backing off.And that...