Just wanted to report that the latest Cygwin will get through part of the make process on 4.0. It dies now with some problems compiling the tcl portion of the server--I'm assuming that's because cygwin provides tcl itself and there is some confusion about defines.
It used to blow up a lot earlier during configure with complaints about pthreads.
Oh, yeah, and configure still complains that it doesn't know how to build shared libraries.
This doesn't mean I'm committing to do the port (wish I could, no time right now), I just thought I'd report what I'd discovered so far.