"Not a Real Virus" I love it!
Seriously? Are you kidding?
I love it when people say "Oh, well... you need to run it as a program so - there, not a virus" the same holds true for torjan's on Windows too you know.
It attaches to an illegal program downloaded through Limewire and is run when they think they are running the cracker, or it's sent from one person to another by iChat with the promise of "There are pictures in that .exe" or whatever the apple variant of an execicutible is.
This is a Virus, this is a threat, and honestly Apple needs to quit the mud-slinging - their OS is just as vulnerable as Windows - it's just Windows is more popular - but there are still programmers and script kitties are still out there with Macs, perhaps a bit spiteful, who are more than willing to take down their system.