We set up AirPrint using unicast DNS-SD on our campus about a year ago and it turned out to be a big success, so we're looking at trying to get AirPlay working so our faculty and students can wirelessly show content on our classroom projectors.
There are still a couple of other things preventing an ideal implementation (username and password authentication, for starters), but I've been trying to set up a working demo nonetheless. Getting AirPrint working was basically just a matter of advertising the same records over a DNS-SD domain instead of the multicast (.local) one, but doing the same thing for AirPlay doesn't seem to cut it. The devices don't recognize the DNS-SD AirPlay servers as available.
I've uploaded a screenshot of my DNS-SD configuration with the original (from AirServer, which works normally for multicast) here.
I realize this is still a fairly new feature and documentation is lacking, but has anyone been able to get AirPlay working via DNS-SD? If it simply only works over multicast, I can accept that, but its potential is so appealing for us that I thought it'd be worth asking if anyone else has figured it out.