It appears Google Talk has started federating with other Jabber servers.
Gary Burd, a Google software engineer,
flipped the switch to
connect the Google Talk Service to the public XMPP network this
morning. Google Talk users can now chat with users on other XMPP
services and vice versa.
One of the most promoted features of Jabber/XMPP (the protocol which
Google Talk uses) is its ability to communicate with other federated
servers, much like email and its ability to communicate with any other
server. You email firstname.lastname@example.org, your mail server contacts someplace.com to send the message. You IM email@example.com, your Jabber server contacts someplace.com to send the message. In
both cases, the domain has to be running the appropriate server. So,
you can't add hotmail.com or yahoo.com people, since neither Hotmail
nor Yahoo are running Jabber servers.
Basically GTalk can now communicate
with users of other Jabber/XMPP servers -- before GTalk was limited to
only other GTalk users. This does
not mean communication
between MSN, Yahoo, or AOL because these services all use difference
protocols. A full explination can be found on the Jabber.org website here.
A few days ago Google opened up their staff's
XMPP server to the world, and it was anticipated that this was in preparation
for the opening of Google Talk.
News source: Planet Jabber