Pre-compiled clients are on my to-do list. Obviously I want to do this is a systematic manner so that my release process is more repeatable than "find boxes running the following operating systems: ... and borrow them for a few minutes to build a binary".

I'm not sure if it's possible to build binaries using cygwin which will then run without having cygwin installed. If not, this would turn into "port tarsnap to Windows", which is also on my to-do list, but much lower down.