I had an avahi probleme due to thuis missing user.
I recently updated avahi to 0.6.22_0 (from 0.6.17_0). It fixed the missing avahi
user problem.
 But I'm still having an issue, apparently similar with Paul's one.

Console log:
24/03/2008 12:05:13 PM org.freedesktop.avahi-dnsconfd[522]
Failed to connect to the daemon. This probably means that you
24/03/2008 12:05:13 PM org.freedesktop.avahi-dnsconfd[522]
didn't start avahi-daemon before avahi-dnsconfd.
24/03/2008 12:05:13 PM com.apple.launchd[1]
(org.freedesktop.avahi-dnsconfd[522]) Exited with exit code: 1
24/03/2008 12:05:13 PM com.apple.launchd[1] (org.freedesktop.avahi-dnsconfd)
Throttling respawn: Will start in 10 seconds
24/03/2008 12:05:14 PM org.freedesktop.avahi-daemon[523]
Found user 'avahi' (UID 502) and group 'avahi' (GID 502).
24/03/2008 12:05:14 PM org.freedesktop.avahi-daemon[523]
Successfully dropped root privileges.
24/03/2008 12:05:14 PM org.freedesktop.avahi-daemon[523] avahi-daemon 0.6.22
 starting up.
24/03/2008 12:05:14 PM org.freedesktop.avahi-daemon[523]
WARNING: No NSS support for mDNS detected, consider installing nss-mdns!
24/03/2008 12:05:14 PM org.freedesktop.avahi-daemon[523]
dbus_bus_get_private(): Failed to connect to socket
/opt/local/var/run/dbus/system_bus_socket: Connection refused
24/03/2008 12:05:14 PM org.freedesktop.avahi-daemon[523] WARNING:
Failed to contact D-Bus daemon.
24/03/2008 12:05:14 PM com.apple.launchd[1]
(org.freedesktop.avahi-daemon[523]) Exited with exit code: 255
24/03/2008 12:05:14 PM com.apple.launchd[1] (org.freedesktop.avahi-daemon)
Throttling respawn: Will start in 10 seconds
24/03/2008 12:05:23 PM org.freedesktop.avahi-dnsconfd[524] connect():
No such file or directory
24/03/2008 12:05:23 PM org.freedesktop.avahi-dnsconfd[524]
Failed to connect to the daemon. This probably means that you
24/03/2008 12:05:23 PM org.freedesktop.avahi-dnsconfd[524] didn't start
avahi-daemon before avahi-dnsconfd.
24/03/2008 12:05:23 PM com.apple.launchd[1]
(org.freedesktop.avahi-dnsconfd[524]) Exited with exit code: 1

Would reinstall avahi solve the problem?
I have seen very few thread about the topic.
Paul, did you manage to get a working asahi?

Thanks,

--nodje