Linux Mint was where I started testing, and that's Ubuntu based, I think.
Even without the raw XNS code support, compiling Maiko (on my ethernet branch) with `./makeright [ x | sdl ] NETWORK=NETNUB` you can get an emulator that works with the Dodo provided XNS services, which include clearinghouse, filing, and mail. Dodo is a little fiddly to configure. Lafite (the mail user agent) with UNIXMAIL loaded can retrieve mail from a /var/spool/mail mbox file and store it in a lafite folder without network code, but I have managed to have it talk XNS to the Dodo implementation of Mail service, and it works.