I am in transit, in Boston, so I haven't had a chance to talk to any other folks involved in this effort, but I will do so next week, but I got a pointer to this info from Peter Saint-Andre emailed the link to me:

[from Jabber Press]

The Jabber Software Foundation (JSF) today published initial documentation of Jingle, a set of extensions to the IETF's Extensible Messaging and Presence Protocol (XMPP) for use in voice over IP (VoIP), video, and other peer-to-peer multimedia sessions. The Jingle technology represents an open version of the protocols used in the popular Google Talk application released in August 2005, and Google is supporting the standardization and evolution of these protocols through the JSF's community standards process. The specifications published today are:

• JEP-0166: Jingle Signalling -- The core technology for peer-to-peer session management, which enables communication through existing firewalls and can be extended to support a wide range of session types. (Authored by Scott Ludwig and Joe Beda of Google, Peter Saint-Andre of the JSF, and Joe Hildebrand of Jabber Inc.)
• JEP-0167: Jingle Audio -- The session description format for Jingle audio sessions, enabling seamless one-to-one voice over IP (VoIP) between Jabber/XMPP users. (Authored by Scott Ludwig of Google and Peter Saint-Andre of the JSF.)

Follow-on specifications will be published in the near future for additional session types (e.g., video) as well as to document interoperability with the IETF's Session Initiation Protocol (SIP), the ITU's H.323 technology, and the IAX protocol used natively in the popular Asterisk open-source PBX application.