These postings are reminiscent of an earlier full-scale cyberwar between Israeli and Palestinian hackers—a conflict that Israeli officials believe caused noticeable damage to the country's economy four years ago. They are also a powerful reminder of the continuing threat of cyberterrorism, an issue that has caused growing concerns among national-security experts in recent years. Indeed, many experts say, the potential vulnerability of the United States to a sophisticated cyberattack is far greater than is generally understood by the public. Among the vital public services in the United States that rely on digital controls, making them potential targets for a cyberattack, are public utilities (including electrical power grids), transportation systems and broadcasting networks, experts say.
Update: Gwhizkids at alt-ctrl-del links and raises issues of denial of service and the ease of cyberattacks. Absolutely right and supported by recent denial of service attacks on anti-spyware sites here