The web site of the Recording Industry Association of America has been offline for more than a day, following several days of intermittent outages. The www.riaa.com web site was targeted for a DDoS attack by the MyDoom.F virus.
The DDoS component of MyDoom.F also targets www.microsoft.com, which has experienced no significant problems. Antivirus vendors say MyDoom.F has been found on as many as 45,000 machines. A dynamically updating graph of the sites targeted for DDoS by various MyDoom variants is available here.