Until recently, Apple has enjoyed relative immunity from malware. It simply didn't make sense for developers to create spyware, viruses, and the like for an operating system. Windows devotees were happy to point out that this was largely a function of market share rather than any special system security features.
Now, however, a name popped up in the news that I featured in a couple of blogs last year regarding OLPC ("And more from the OLPC front" and "Intense (and really thoughtful) ranting from the OLPC front"). Ivan Krstic was OLPC's security guru until he left the organization about a year ago. Read this blog post: he didn't leave on good terms (warning: the language is a bit rough, but it's a good read).
Apple, to their credit, has hired him, presumably to work on security within their own OS. Obviously, Apple isn't getting help from OLPC, but Krstic's unique approach to malware at OLPC just might be precisely what Apple needs to deal with security proactively instead of through obscurity. ZDNet's Ryan Naraine goes into a lot more detail on his related blog post:
Instead of blocking specific viruses, the system (Bitfrost) sequesters every program on the computer in a separate virtual operating system, preventing any program from damaging the computer, stealing files, or spying on the user. Viruses are left isolated and impotent, unable to execute their code.
Sounds good to me. The idea of installing anti-malware software at all of my Mac-based schools was bringing me down.