"Regardless of your opinion of Apple and its approach, the fact
is that the computing landscape is irrevocably changed in the wake
of MacDefender and--later--MacGuard. While these certainly weren't
the first bits of malware to target Macs, they were among the few
to succeed so well....
"Two closed desktop operating platforms have now "fallen" to
malware, in other words. That leaves the open one still standing: