There is a 9vx binary built for Lion on Jan 27, 2012 at http://code.google.com/p/nix-os/source/browse/9vx.OSX
Just tried it out briefly on Yosemite (10.10.5), and, within the limits of such a short attempt, I can say that it seems to work. Going full screen at first left a part on the right blank, but this was restored later on. Mark.
