Neat! From a quick look, it seems they still depend on the upstream 'nxagent', which makes me sad.
For those unfamiliar with NX's innards, 'nxagent' is the somewhat opaque name that NoMachine gave to the actual X server that's been hacked to run headless, display on other X servers via the NX protocol, and reconnect to the remote X server open request -- i.e., the part that provides the core functionality. What Google's released is a rewrite of the management scripts that surround this core -- the way you connect to an NX session is that you ssh in as the magic user 'nx', and then speak a special protocol to log in again as your actual user, and then speak another special protocol to manage sessions, and then get a proxy to the actual underlying nxagent. Various programs are needed to implement these protocols, spawn and manage the actual nxagents, proxy to them, etc. The freenx implementations are rather grotty, as mentioned, and Google's look much cleaner. Really what *I* want is a way to skip them altogether, though, both aesthetic and practical grounds.
Unfortunately, nxagent itself is (last I checked) a forked version of the old XF86 monolithic tree, developed by a "occasionally throw a big pile of undocumented tarballs over the wall" method, and it *should* make it easy to get a simple persistent X session running under a single user account, there are some restrictions that make it hard. I don't remember exactly what problems I ran into anymore -- hopefully someone will correct me if I'm wrong -- but IIRC you cannot *start* a session in headless mode, only start it in attached mode and then disconnect, and if you tell it that you want to reconnect but fail to do so within 30 seconds, it will just quit and take down all your running programs. If your wireless drops out at the wrong time then sucks to be you.
(Standard disclosure/shameless plug: I was so frustrated that I wrote a competitor, 'xpra'.)