For a long time, Macs were generally considered fairly safe in terms of malware because there wasn't very many Macs out there. The fact that the number of Macs was relatively small compared to the countless PCs deployed in universities, offices and homes around the world meant Windows machines were a much more likely target for cyber villains. However, as the Mac brand has grown in popularity, the machines are more at risk for malware attacks.
In an apparent effort to bolster Mac OS X security, Apple has hired a security expert that previously worked on locking down Microsoft's Vista OS. Kristin Paget was hired by Microsoft, along with a few other hackers, to try and find bugs and holes in Windows Vista. Now it seems Piget is working with Apple.
Wired reports that Paget's LinkedIn currently has her listed as a core operating system security researcher at Apple. While she wouldn't comment on the nature of her work (Apple also declined to elaborate on her employment with the company), the title would suggest she's lending a hand to keep OS X air tight.