RendezvousRendezvous is a computer network technology used in Apple's Mac OS X from version 10.2 onwards. It uses standard DNS packets in a new way. Thus it is a new service, but it is using a technology that is relatively old, DNS over IP.
It is used for iTunes to find music shares among different computers via networks. It is also used by iChat to find other iChat users on the LAN. Rendezvous is Apple's trade name for its implementation of the IETF Zeroconf protocol.
Without special DNS configuration, Rendezvous only works on a single subnet. There seems to be a misperception that a service made available over Rendezvous is "on the Internet", or available to the world-wide users of the IP network known as the Internet. This is not true. Services are automatically made available to only the users of a single ethernet network, which usually encompasses a fairly small area.
See also: Universal Plug 'n' Play