Mac antivirus and malware software (Is it needed?)

Mac antivirus software FAQ: What Mac antivirus software should I use? (Also written as, "Do I need Mac anti-virus software?" or "Should I use any Mac antivirus software at all?")

Apple's new Mac OS X antivirus/malware business

Hmm, it looks like there might be more than one reason for Apple retiring their famous Mac/PC commercials -- turns out they've quietly gotten into the malware/antivirus business.

MacWorld reports that Apple has quietly snuck an anti-malware (antivirus) update into the latest round of Mac OS X Snow Leopard updates. An antivirus program was included in Snow Leopard, and last week's Snow Leopard update included an update to the Mac OS X antivirus definition file (a simple Mac OS X plist file).