Mac OSX is also more and more in the needs of AV software - just wait for it.
Apple already has already AV sofware listed on their website. Once Linux becomes (if ever) a main stream OS it is also in the need for a AVs. Btw. at the security class at univ we only "hacked" and "infected" UNIX based OSes. Since then all the stuff that
you, corona, are saying, about security in UNIX seems so ridiculous to me. It's as infectable as everything else... as long as you run a software that has bugs a backdoor might probably exist.
With UAC activated in Windows Vista/7 you can do exactly as much as if you crack a UNIX system open under a normal user account...
All the AV software that exists for Linux and Mac OS X is to protect WINDOWS users from ge3tting mail sent through mail
servers that run OS X and GNU/Linux. Linux and Mac OS X are literally IMMUNE to viruses and Malware.