I tested CYGWIN_NT-6.1-WOW64 KUWASHIMA-PC 1.7.18(0.263/5/3) 2013-04-19 10:39 i686 Cygwin.
But I don't test complex case. Vagrant test is not all green.
You must patch to HEAD of ffi and Vagrant.
Simple way:
clone my folk, checkout patched branch, bundle install and rake install.
Install bsdtar from setup.exe.
Add virtualbox *.exe dir to PATH in your shell.
run 'vagrant box add centos http://puppet-vagrant-boxes.puppetlabs.com/centos-59-x64-vbox4210.box'
run 'vagrant init'
run 'vagrant up'
add: Test ok this Vagrant+Chef project https://t.co/cdKMSM7jev