A newly surfaced version of the Duqu trojan indicates that the authors of one of the most sophisticated computer worms in recent memory are aggressively trying to figure out how to attack their next target. 

The Conficker worm was one of the more intriguing and potentially destructive pieces of malware in the past decade.  Earlier reports have suggested that Stuxnet was created by the US and Israeli governments, and now Reuters has a source telling them Conficker was also used to negate Iran's nuclear program. 

Despite no official confirmation by the Pentagon, it's a very safe assumption that the US created the Stuxnet worm (with Israel's help) to take Iran's nuclear reactors offline.  But when it was first discovered, it seemed too sophisticated for Earthlings.