I seriously doubt that 600,000 macs were infected... How do we know this number is correct? Because a completely unknown security firm that sells Mac antivirus software ("Dr. Web", a russian antivirus company) tweeted about it!
Fair enough, with one caveat: Everyone who trumpets security/anti-virus company press releases about Android should be required to shout about 600k Macs just as loudly. I wonder how many will.