Google has adopted Jingle as the default protocol for Google Talk. Jingle is an extension of the XMPP which allows for peer-to-peer and session control (signalling) for multimedia interactions such as VoIP and videoconferencing.
The protocol was developed by Google, Collabora, Yate, Tandberg and Jabber Inc. Others that support it include Asterisk, FreeSWITCH, Nimbuzz, and Pidgin. Imagine a P2P protocol that lets the thousands of Asterisk-based PBXs to communicate with each other using XMPP. Taking the Asterisk ecosystem along with other large user bases from Nimbuzz, Google Talk, and potentially others could potentially build the largest P2P VoIP / video conferencing network in the world. Bigger than Skype. Least, that's the promise XMPP holds.
Peter Thatcher of Google said in his announcement to the Jingle developers list that “the future is Jingle,” and went on
It would be nice to see a standardized P2P VoIP protocol and even see Skype support it, though I doubt that will happen. With Google announcing plans to build a VoIP client into the browser just a couple days ago, and now today's news, Google is clearly making aggresive steps within the VoIP arena. I wouldn't be surprised if a new entirely revamped version of Google Talk is released soon.
“I hope that this will be a support to the Jingle community and futher our efforts to have open standards for voice and video communication.”
Via XMPP Standards Foundation