I was pleasantly surprised to find avahi installed as part of os2008. It's running in order to find zeroconf/bonjour services, but it's not advertising any services by default. The first thing that I did as a mac user is to name the device.

As root, edit /etc/avahi/avahi-daemon.conf

uncomment host-name and give your device a more friendly name like

host-name=hodge-podge

restart avahi by...

/etc/init.d/avahi-daemon restart

and now you can, from your mac.

ssh root@hodge-podge.local

This will work anywhere you are on the same broadcast segment as your NIT. No need to ifconfig to find the local address of your device!