Stuxnet Struck Five Targets In Iran
Batblue writes "Researchers at Symantec said that the notorious Stuxnet worm targeted five separate organizations, and attacks against those objectives — all with a presence in Iran — started in June 2009, more than a year before independent experts raised the alarm."
Of course, most anti-virus software is reactionary based off previous viri found in the wild. They're reversed engineered and a solution is rolled up into the next set of scheduled updates. Most of the time, anti-virus is good to have for the home user and/or small and medium business. But if your organization is explicitly targeted with custom code, most anti-virus software will do squat to help unless you provide them exploited code to reverse engineer.
Life is not for the lazy.