In Rare Attack, Malware Targets Macs
online.wsj.com
online.wsj.com
So not a security hole, but a website with a .png of the software update box or something?
A larger number of websites/phishing emails try to trick you into entering personal details... just one of those things.
(Also, I'd place at least some blame on the people trying to trick you into installing malware, however stupid you'd have to be to actually do it.)
I wonder if this was carried out by a disgruntled Mac hater (maybe ex-girlfriend was a Mac user?).