XMPP/Media Library is a .NET library for XMPP, TLS, RTP, and STUN, SOCKS that supports Windows, Windows Phone and Mono.
The XMPP/Media Library provides the XMPP client libraries for Windows and Windows Phone 7.
The XMPP clients for Windows Phone have been tested against open fire, jabber.org and Google Talk.
The author states that
The intial goal of this project was to transfer some of my homebrewed home automation audio/video streaming projects to windows phone. XMPP seemed like the ideal protocol for control since it wasn’t limited to a given network like UPNP/Bonjour. This led to the development of an XMPP library and the challenges of making a relatively simple protocol work on windows phone.
You can download XMPP/Media Library for .NET and Windows Phone 7.5 here