And, actually, except for this one outbreak where the damage wasn't actually all that serious, Mac users have confronted very few malware infections, and most are social engineering affairs, where you make a decision to install or download something that may cause harm. There is still no demonstrated need to run security software. Apple's Unix-based OS X debuted in spring of 2001, and over 11 years later, the OS is still quite safe if you just watch the links in your email and suspicious sites.
These days, Apple offers built-in protections against potential malware, particularly in the most recent OS versions. They have also offloaded support for Flash and Java to their respective publishers, who are responsible for fixing security lapses and providing automatic updates.
