After all the hoopla that the above mentioned knowledge base article created, Apple has quietly withdrawn that recommendation.

You can read more about the controversy in the Tidbits article here .

The conclusions of the article:
"The reality remains that although Macs are far from immune to security issues, there is very little malicious software that targets them. Macs can be affected by malware on occasion; I've been contacted twice in the past year by people who downloaded and manually installed malicious software onto their systems. I also work extensively with security researchers who tell me that Mac OS X's built-in protection technologies can be circumvented by an experienced attacker. But neither I nor the security researchers with whom I work know of any widely deployed exploits for Macs. Unless you are either specifically targeted by a knowledgeable bad guy, or spend a lot of time downloading software from risky sites, the odds are extremely low you'll ever encounter malicious software. Macs aren't inherently more secure than PCs, but they are practically never targeted, dramatically reducing the risk a Mac user will be compromised."

And their general recommendations:
"1. Everyone should use an email service that filters spam, viruses, and other malicious software (such as MobileMe, Hotmail, Yahoo! Mail, or Google Mail).
2. Enterprise users often need to install antivirus software to comply with corporate policies and avoid being a vector to infect their Windows-based coworkers. Any of the major antivirus solutions work well, and you should work with your corporate IT department to determine what to install.
3. If you visit risky sites (adult, gambling, and file sharing sites are the major ones) and download software from them, you should consider installing antivirus software. Of the two major pieces of malicious software we've seen this year, one disguised itself as a plug-in to view adult videos, the other as a poker program.
4. If you are running Windows on your Mac, via Boot Camp or a virtualization tool like VMware Fusion or Parallels Desktop, you still need to install Windows-based antivirus software to protect your Windows installation.
5. Generally, other Mac users don't need to install antivirus software at this time, but I advise you to stay abreast of security news in TidBITS, just in case the situation does change. Email filtering will likely protect you if there is some sort of sudden outbreak, but it's entirely possible that Macs could become a more common target in the future."