Install the update.
The article has a link to an f-secure article that tells you how to fix it.
Threat Description: Trojan-Downloader:OSX/Flashback.I
And yes, this isn't a self replicating virus but it is pretty hairy malware.
Safe browsing practices help.
Using Opendns or dyndns internet guide can help too. They will warn of potentially bad sites.
OpenDNS Internet Security - Malware Protection and Botnet Protection
Internet Guide | Web Content Filtering | Parental Internet Control