When searching for the source for Stuxnet, its relatively easy to come by in one form or another. Although I'm actually curious if anyone has done any work to comment the source and perhaps clean up variable naming and so on.
My real question is if anyone is aware of a source for the "Flame" virus source code. Its often mentioned as being the most advanced virus observed, so it would be interesting to see the source.
I can't find any (decompiled) source code of it, but I did find a rather thorough CrySys(Laboratory of Cryptography and System Security, Budapest) technical report (pdf). It covers pretty much all aspects of it, from how Skywiper works to how it propagates and infects. A short digest of it can be found in this blog (among many) and a few more links to other anti-virus labs' blogs here. I realize I didn't answer your question, though. I guess it's still too early for any of these labs to share their newly found lab pet and its thoroughly dissected innards with the rest of us. Their eyes probably roll not unlike the fruit slots machines do on a jackpot roll, and I wouldn't keep my hopes up that they'll release more on it until their eyes finally settle on banana. ;)