Disguised as a link to a video, the koobface virus will take over your computer and use it to attack other systems. It's a nasty critter, but not really new. However, your antivirus may not protect you. This virus spreads by sending a link to an infected computer user's "friends" on social networking site like Facebook and Twitter. This link, when clicked upon, downloads and installs the virus.
The best way to avoid getting stung by this virus is to never download anything from an email link and make sure your antivirus program is active and the definitions are current.