I'd really like to know specifics. It obviously had to be an executable file. There were no warning messages, such as when you try to launch a file downloaded from the web?
Many years ago, when I first started riding Harleys, friends would say things like, "I know a guy who was killed on a motorcycle." Now, I understand their intent was to show concern and be helpful, but after hearing that so often, I started asking details. "OK, exactly what happened?" The answers usually involved, "Well, he was drinking and.... " or "he was racing another bike and...." or "he was doing a wheelie on ice and...." As it turned out, most of the time, it wasn't merely the bike that killed them; it was drinking or speeding or doing stupid stunts.
So when I hear "someone got a virus on their Mac" or "malware attacked their Mac" or " someone I know had ended up getting something through iChat that had corrupted the system", I'm naturally skeptical until I hear verifiable facts.