Run for the hills!
Well here's a story I found on CNN, because with all their Apple lovin' they have to show they are still somewhat unbiased.
Worm targets Macs through Bluetooth
That's scary, isn't it? Well here's the counterpoint, provided several days in advance for your viewing pleasure:
Yet another pointless worm Inqtana
Granted, a fan of the Mac platform isn't going to scream bloody murder at the first sign of these things. Which raises the constant specter of laziness. That's a social vector too-- thinking you can't get a virus when you can and doing nothing once you've been warned.
Good news: so far I have yet to see anything so destructive or easy to infect and do damage on the Mac as on the PC. So for now you are safe, in my opinion (patent pending). If you want to be paranoid, switch to FreeBSD and wear a tinfoil hat.