I've recently dug into trying to understand and apply the C++ volatile qualifer. Unable to fathom the compiler's handling of volatile primitive types, I posted to comp.lang.c++.moderated asking for guidance. The resulting exchange with Andrei Alexandrescu has been quite illuminating. Turns out that it's a whole lot harder to write correct multithreaded C++ programs than I previously appreciated.

The exchange of postings is archived on Google Groups and is well worth a read if you're concerned with concurrency issues in C++:

comp.lang.c++.moderated : volatile-qualified primitive types