Mac users have been targeted by a phishing scam - alerting the presence of a computer virus, then offering a MacDefender software as the solution.
This offered software is identified as malware, and is out to just get the user's credit card info. Apple has issued a document on how to avoid or remove this malware.
I hope nobody got victimized with this phishing scam.
How to avoid or remove Mac Defender malware [site link]