I learned about Nono when Austrian playwright and novelist Thomas Bernhard (famous among music lovers perhaps for his Glenn Gould novel) mentioned him in an interview, saying Nono would be the only one he'd be interested in collaborating with (on an opera, I guess). This was some time during the seventies, I think.
Thanks to YouTube, I've recently been listening to some Nono. He's intruiging to say the least. So far I've listened to ...sofferte onde serene..., No hay caminos, Cori di Didone and Contrappunto dialettico alla mente.
In a way, this is perhaps the only music that still made sense in a post World War II Europe, where god had died and Auschwitz was real.
By the way, there is an hour-long documentary up on Youtube called Abbado . Nono . Pollini