"and if you’re on OS X 10.6.7 it will update the definitions on a daily basis to catch new variants". Right there, in the linked article.

See http://support.apple.com/kb/HT4657 for details.

Here are the definitions: http://configuration.apple.com/configurations/macosx/xprotec...

Right, so just hope Apple gets a copy of the malware before you do.

Given the current scope of the problem, this is an appropriate solution.

Of course, is there any alternative? Heuristics aren't a good solution.

That's what antivirus is, essentially; it doesn't replace real security, but it can help.

I'm glad to see Apple realizes that it should be part of the OS, not a choice between bloated third-party poorly-integrated expensive trialware applications, as is the ridiculous status quo elsewhere.

Further, it's great to see they're doing it right: it's invisible to the user.

No pop-ups, no opt-ins, no alerts. It does its thing, and if you really want to opt-out, you have the option to do so.