Stuxnet, Duqu, and Flame are all pieces of malware which have been covered by the larger news outlets for their apparent design to target and damage Iranian nuclear facilities. After investigation by security researchers it has been determined that Stuxnet and Duqu are directly related, while Flame is more indirectly related. Now a new piece of malware has struck some of these facilities, but it probably isn't connected to the three before it.
The report of the new malware comes from a Finnish computer security firm which claims a scientist at the Atomic Energy Organization of Iran had contacted them about their systems being infiltrated again. The malware was able to shut down the automation network at two facilities but did a little more than just this sabotage, and that bit more is why it is not as likely that this is related to the malware described above.
Supposedly several workstations were on in the middle of the night at these facilities blaring what the scientist believes is Thunderstruck by AC/DC. As the other three previous pieces of malware operated more secretly, this attack more likely is from a thrill seeking hacker. Until the story is officially confirmed and analysts can examine the malware, we cannot be sure.