I've been running this for over a year now and it is great!

I did run into a problem at work when we upgraded the linux box I was using to braodcast a mDNSProxyResponderPosix beacon pointed towards my Gentoo box at home. The problem was the rules in our new iptables firewall. Here's the addition to the firewall chain I made:

-A RH-Firewall-1-INPUT -p udp -m udp -s 139.57.49.1/24 --dport 5353:5353 -j ACCEPT 

* All one line, and where I have RH-Firewall-1-INPUT you'll want to put the name of the main chain for your firewall.

So for people trying to Google this answer (as I was) the port number for Apple Rendezvous is 5353, running UDP.

Setting up mDNSProxyResponderPosix is a seperate issue, but if you get the source code from Apple's darwin source code check out the documentation that comes with. Unlike some programs like NetworkBeacon, mDNSProxyResponderPosix doesn't care if you enter a DNS name or an IP.