I just noticed RELENG_5 still doesn't seem to have the ed driver patched for amd64, which would mean 5.5 wouldn't have network as a qemu guest. How about updating RELENG_5's ed, or at least committing a patch like the one in http://docs.freebsd.org/cgi/mid.cgi?20050801215410.GA10633 (and adding ed to sys/modules/Makefile and maybe to GENERIC too?)