Rich Mogull, writing for Macworld:
As Mikko Hypponen, Chief Researcher at F-Secure pointed out via
Twitter, if there are roughly 45 million Macs out there, Flashback
would now have infected more than 1 percent of them, making
Flashback roughly as common for Mac as Conficker was for Windows.
Flashback appears to be the most widespread Mac malware we’ve seen
since the days when viruses were spread on infected floppy disks;
it could be the single most significant malware infection to ever
hit the Mac community.