I've had to redo interrupt handling in SBCL/Win32, and also rewrite thread suspension and interruption once more. Having done that, now my tests pass. With this in mind, thread support is getting closer to completion. But the volume of changes is getting bigger and bigger which reduces my confidence in swiftly merging this into SBCL HEAD. But it's still manageable as a fork.
I haven't released the code yet since it requires more polishing and some more testing.