Every modern flavor of concurrency, be it STM, Actor Model or why not, will abstract threads and locks but won't remove them underneath. There is no magic. So if this Dylan implementation doesn't even support the foundation yet, that doesn't seem likely.
The thread support depends on the compiler backend. It works on 32 bit FreeBSD, Linux and Windows. The thread support in the C backend is broken, but it nearly fixed and will be in place for the next release, bringing the thread support to OS X and 64 bit Linux / FreeBSD.
I would be curious to find out if you guys ever consider LLVM since you mentioned backend work. How much work do you think it would take to switch your C backend to LLVM?
We're actually working on replacing the HARP native backend with one based on LLVM. The HARP backend is currently x86 only and is what we use on Windows, Linux and FreeBSD. (But not OS X, there we use the C backend for both 32 and 64 bit.)
The LLVM backend will also improve our platform support. I talked a bit more about this in the thread on reddit: http://www.reddit.com/r/programming/comments/n8d6o/open_dyla...
Surely it supports some other form of concurrency?