if you add "-mimicmodel Xserve" to the line in /var/etc/afpd.conf the Picture used in the Finder on Mac OS X will look like an Apple Rack Server.
Patching /etc/rc.d/afpd for this is easy.
Nice to have feature.
Seems to work fine in the same LAN, but not behind a router.
Ok, found my Problem - mdnsresponder broadcasts did not go over my router.
This ticket can be closed.