For those of us working with XMPP, this is probably the best christmas present we could have.
Yesterday, the Jabber Software Foundation, announced two new JEPs (similar to the RFCs of IETF, they define extensions to the basic XMPP RFCs), Jingle Signalling and Jingle Audio, to specify a standard way for XMPP clients to negotiate Voice over IP sessions.
I'm still looking over licensing details and technical details, but the future for XMPP-based VoIP seems a lot brighter today.
BTW, my employer, is happy and proud to be part of the list of companies that pledged support for this standard. :)
Update: I'll be collecting some links to post around the comunity
Update 2: Aparently the libjingle also includes a relay server and a STUN server. From the libjingle readme file (via Celso):
Libjingle will also build a relay server that may be used to relay traffic when a direct peer-to-peer connection could not be established. The relay server will build in talk/p2p/base/relayserver and will listen on UDP ports 5000 and 5001. See the Libjingle Developer Guide at http://code.google.com/apis/talk/index.html for information about configuring a client to use this relay server.
Lastly, Libjingle builds a STUN server which implements the STUN protocol for Simple Traversal of UDP over NAT. The STUN server is built as talk/p2p/base/stunserver and listens on UDP port 7000. See the Libjingle Developer Guide at http://code.google.com/apis/talk/index.html for information about configuring a client to use this STUN server.