An interesting article I came across. It was very funny that 274 of those are in Cupertino. Guess Apple's own employees get infected.
http://news.cnet.com/8301-1009_3-57409619-83/more-than-600000-macs-infected-with-flashback-botnet/
http://news.cnet.com/8301-1009_3-57409619-83/more-than-600000-macs-infected-with-flashback-botnet/