Are you sure about that? I had thought that Rendezvous was designed to operate only within a given subnet. I could be wrong, and if I am, then wow I will be green with envy at your good fortune.
Do a search on VersionTracker for an app called Rendezvous Beacon...it will alert you as to whether there are other Rendezvous enabled Macs on your network. Next, make sure your sharing is enabled in iTunes.
To quote that old Palm Olive commercial, "you're soaking in it right now, Madge." When you are sharing and streaming iTunes on your network, that is rendezvous in action.
Zero config networking.
If you have a wireless laptop, check your print utility the next time your in a wireless zone. If there's a printer-sharing enabled Mac around within that subnet, you'll see it in the list of printers. Neat eh?
Rendezvous is Apple's name for the ZeroConf technology. That is what allows anyone on the same network (All of U of T must be on the same network if howing is seeing so many) to automatically be able to connect or see information.
For example, in iTunes, it will automatically see anyone sharing their library. In iChat, there is Rendezvous messaging, which is great for messaging across a network. Other apps like SubEthaEdit allow you to share documents and people can join in and see the document right away.
It makes connecting devices (like printers), applications and documents seamless and dead simple across a network.
It's an awesome technology, but you don't actually turn on Rendezvous, its just a feature, and something that is device/app specific. (eg. You don't have to share your library on iTunes, so it doesn't broadcast that your library is available). Just wait until iPhoto 4 is out with Photo sharing That could be really, really interesting.