I believe Matthias Melcher was originally providing the Windows builds, back when Einstein was hosted on Google Code, but hasn't created any recently (I'm not sure how much he's using Windows these days). The most recent improvements to Einstein (esp. over the last few years) have been related to Android, OS X, and iOS support, so the Windows build has gone mostly untouched. It might stilll build using cygwin, but I'm not sure.
The source code is all there, so anyone running Windows who wants to try to get it running is certainly welcome to, but my guess is it'll take a little work. That said, it'd get the codebase updated for easier Windows releases.
Wait a sec... where's the page/thread that was curated/updated by a gentleman from the Netherlands? I cannot find it now (last looked probably a few months ago). I don't believe that was Google Code, but when did Einstein migrate off?
I used to get my builds from there; though maybe they were just someone's builds... Does this ring a bell?
Trying my hand at it - the non-Xcode Jamfiles are an ancient, horrific mess. First attempt with Cygwin blew up horribly - it just doesn't know how to build K, full stop. Tried again on an Ubuntu box, can't find cdefs, install 32-bit libraries, and then it can't find its own files. My Mac is too old to run a newer Xcode to build the (presumably better maintained) OS X version.