After some wrestling, I've managed to get 10.2's built-in NAT to work. I'm using my machine's built-in ethernet for my external connection and a PCI ethernet card to go to my switch. My machine inside the network can see the server with Rendezvous in iChat (I show up in its Rendezvous buddy list) however the server can not see it and they can't trade messages.
My best guess is that my server is scouting for Rendezvous playmates on the wrong network port (built-in instead of PCI), and I'm wondering how I can fix this? I have no idea what my network settings should be for the PCI ethernet card and anything I've tried doesn't seem to have much (or any) effect on the situation.
Can anyone help me out?