Not to get mixed up in your little tif here, but OS X has had malicious scripts for a while. Lightwave 7, the underground version had a crack available that was actually a malicious script, when triggered, deleted the entire home directory of the user. There are a few unix and applescript executable files out there that can really eff up a Mac, but do they propagate? Do they spread through contact lists? NO.
Why? Because the core foundation of OS X is not like Windows, which is built primarily on Internet Explorer (or, was, until Vista), which allows malicious code to get anywhere it wants to. OS X locks anything down that enables this.
Macs have had viruses in earlier versions of the OS. So has Unix. But let's not forget that Unix is the grandfather OS these days, OS X is built upon it, and Windows still has millions of lines of legacy code that MS neither wants to correct, nor will correct, therefore allowing viruses to plague them.
I'm sure there are tons of Linux and Mac programmers that write malware for windows. Why not? Windows, after all, was stolen and has since integrated stolen and squandered software developers work.
edit: Erendiox, don't bash the honda civic, it's lasted me 10 years now! lol