Protect your Mac from Flashback--run Software Update!
Apple released a security update on April 16 that removes the most common variants of the Flashback Trojan horse. People with Macs running OS 10.6 and higher should run Software Update right away to install this update.
NOTE: If your Mac runs an OS older than 10.6, the safest thing is to turn off Java in the Java Preferences app in your Mac's Utilities folder.
For more information, see: http://oit.cfans.umn.edu/support/safecomputing/flashback/index.htm