I've got multinet working on Linux, for those that are interested.
Sourceforge appears to be sulking at the moment so I've uploaded the latest dnprogs
sources to
http://chrissie.fedorapeople.org/dnprogs-2.44.tar.gz
and to Debian.
Instructions for setting it up are here:
http://linux-decnet.wiki.sourceforge.net/multinet
Have fun, and let me know how you get on.
Chrissie