ZDNet UK - News - Code for MSBlast variant posted online : This slightly misleading title warns that the threat of a new worm based on the recent MS ASN vulnerability.
Patch your systems NOW - go to the windows update site, apply ALL critical updates! If you don't, then in a few days when this source is used to develop a really nasty worm like Slammer or Blaster, your machine will be owned in mere moments. This is not just another patch - this is arguably more important than any patch in the last few years.
Remember, the CODE IS OUT - people have posted actual working code on how to exploit this vulnerability, and you know that the hackers have taken the code and will be developing a whole raft of customized viruses and worms to release that can do anything from crash your computer to completely take it over and use it to spread further, transmit spam to millions of people, or worse.