It's work in progress, however you may want to take a look at https://rust-lang.github.io/unsafe-code-guidelines/. As far thread safety goes (threads, locks, atomics), memory model matches C++ specification.
I believe it's safe to assume that Rust's memory model is (a subset of) C++11's memory model, since that's what LLVM implements. At this point I don't see how any specification could deviate significantly from that without breaking tons of code.
The Rust memory model is deviating from it a little in order to enable some norestrict-based optimizations that aren't really done for C, even though (as you know) LLVM can't really take advantage of them yet.
