A nuclear facility that allows flash drives, they deserve to be a target.  Stuxnet just combined a lot of known exploits with insider knowledge. Happens quite regularly but companies keep it quiet. 
TDL4 rootkit is a lot more of a threat to the world than something like stuxnet. It infects windows 7 , 32bit and 64bit, bypasses driver signing requirements, and makes itself invisible to detection software, silently doing damage in the background. It is kind of funny because it removes other malware on the system to keep the user from noticing something is wrong. It patches the drivers windows uses to interface the hard drive so the OS is always communicating through the malware and of course it tells the OS everything is fine, no need to look for anything wrong here.
http://resources.infosecinstitute.com/tdss4-part-1/