<p>My organization is considering using Jabber as an agnostic device to device to application messaging protocol.</p>

<p>Does anyone know of the best practice existing Microsoft competitor to Jabber?  Or, an emerging competitor?  And, if so, a good URL reference to get a jump start?</p>

<p>Website for Jabber:
<a href="http://www.jabber.org/web/Main_Page" rel="nofollow noreferrer">http://www.jabber.org/web/Main_Page</a></p>

Jabber is several things : the older name of the  Extensible Messaging and Presence Protocol (XMPP), the jabber server and application, and the jabber network.
Windows Communication Foundation
is a web-service based API for communicating between applications?
Office Communicator is an application that uses SIP/SIMPLE messaging protocol.
What do you really need? The application or the protocol/api with which to build an application?