The Digital Audio Control Protocol (DACP) was recently introduced by Apple, and is built into all recent iTunes versions. DACP is the protocol used by the Remote app on the iPhone/iPod Touch to remote control your desktop or laptop iTunes player.
DACP is similar to the well-known DAAP, using Bonjour MDNS to find libraries, then using HTTP requests with binary responses to transfer data. Remote is an attempt to build a full featured Python/GTK client to control iTunes and other DACP enabled players.
I used the good work of Jeffrey Sharkey dacp.jsharkey.org/ to figure out the protocol as well as the pairing code from jinxidoru.blogspot.com/2009/06/itunes-remote-pairing-code.html This works out of the box without installing any extra software on your PC or Mac.
I have most of the network functionality now working, and I need to spend some efforts on the user interface and the Bonjour discovery and pairing.