[Skritter guys: If this is annoyingly off-topic, please feel free to delete it.]
I've just published an interview in Spanish with an Italian polyglot who speaks 10 languages, most of them with a near-native accent. His Chinese is still a work in progress but his English and Spanish are amazing and even his Swedish is really good.
Here's the link; if you can't read Spanish you can still check out the videos. He has quite a few on his YouTube channel.
http://www.nolapeles.com/2011/02/15/consejos-para-mejorar-el-acento-en-ingles/
My interest when I see this level of accomplishment is always to ask HOW the person managed to do it. We can throw up our hands and say "he's a genius" or we can try to break down his techniques and figure out what exactly he did to get to this level.
I think the key point here is that Luca TALKS TO HIMSELF. When he can, he speaks with natives as much as possible, but the core of his technique is to go through Assimil dialogues, reading, listening, and repeating things to himself.
If you want more detail, there are several links to blog posts in English at the end of the interview.
James