This seems to be real. A number of sources have reported it. Although when I first read the headlines I was hoping it was something other than it was.

As far as I can tell the music simply indicated a compromised system. However, back in the way back times, if you programmed the seeks on a large disk drive you could get it to play 'music' of a sort from the resonance of the stepper motors. I had wondered if someone has changed stuxnet to modify the centrifuge speeds to play notes, and then have the facility play heavy metal music (which would be appropriate for a facility that was purifying a very heavy metal).