Things have been really quiet on Macintosh-front, virus-wise. In fact, I've had several of my hard-core geek friends migrate to Macintosh over the last years...especially to the nice new laptops they have, running unix-based operating system and all. And of course, no virus-worries.
Well, turns out some real malware for OS X has been found. This one, known as "Opener", is a bash script which copies itself as one of the startup items that copies itself to all mounted drives. It seems to be pretty nasty as it contains destructive functionality, a keylogger, a backdoor etc.
Back then in late 1980s viruses used to be a much bigger problem on Macs than on PCs. Then things changed. We here at F-Secure used to have an antivirus product for Macs for years, but we discontinued it after the macro viruses died out as there was so little market for it.
For more info on Opener, check this thread at Macintouch.