That whole story is very shady. He claims that the internal wireless drivers are vulnerable, but that Apple presssured him not to do his demo with them. In the same breath, he says that all OSs are vulnerable, but he did it on a Mac because Mac users are smug. He claims you don't need to have joined an access point, and then joins an accesss point. He claims he has full control of the machine, but then nevers really appears to have root. He claims all Macs are vulnerable, but then says he changed some default settings. Etc, etc.

None of this is to claim that the vulnerability doesn't really exist, that Macs have some magic shield that can't be penetrated, or that we Mac users aren't sometimes insufferably smug. I'd just take this particular demonstration with a grain of salt.

I'd also say that this demo proves that the old "Macs don't have viruses because nobody bothers to attack them" is just plain wrong. There's plenty of people attacking Macs. They are inherently more secure than Windows, though Windows is catching up. And, at some point, there will be a nasty Mac virus. Keep good backups, my smug Mac brethren.