Apple customers have been in for a rude awakening with the recent MacDefender malware problem. The trojan malware tricked unsuspecting users to enter their admin passwords and even credit card information. AppleCare staff were instructed not to assist with the removal of the malware, but that may have been because Apple was planning to send out a security update to take care of the problem.
That security update arrived today and it's called Mac Security Update 2011-003. The update should hunt down and nuke existing MacDefender malware installations and prevent future installations. It provides a File Quarantine definition for MacDefender as well as for its variants and will update its definitions daily for OS X 10.6.7 platforms.
The security update has appeared in Software Update where you can download and install immediately. You can also get the update directly from Apple's support and downloads page here. Nonetheless, just be wary of downloading any type of software that claims to protect your Mac, unless it's directly from Apple. Other variants of the malware include Mac Security and MacGuard.