So FreeNX finally has a repository for Ubuntu Precise Pangolin. I've been working on and off it for the past couple of weeks to get it working, but it's not perfect.
For the installation, I'd have to download some esound-client and other deb files from Debian's repository. Apt-Get would tell you what deb files you would need to look for to get the installation going.
For connection, the standard Gnome desktop worked the best, but for some reason the bottom Task Bar panel is missing.
Printing and File Sharing isn't working yet. It looks like I'll have to go hunting in the log files to see what's not working.
I've also tested X2Go in Precise. This is easy, except for the file sharing and printing. Printing is a one-off thing. At first it looks like it's working. On my next connection, it just stops behaving. X2Go also has a difficult user interface, it hurts to use...
Update: It looks like the "missing" taskbar was due to a window resizing issue. If I maximize the NX window, the taskbar is there after all.