What this means is that now Google Talk’s XMPP servers can talk to other XMPP servers such as Earthlink and Gizmo Project. (I had written about GTalk-Gizmo Link Up earlier.) I am not sure if those two companies in specific have turned on the features, but essentially if you have your own Jabber server, you could talk to GTalk. Some have already had success in cross-server traffic exchange.
This day would never have come to pass had Yahoo, Microsoft, and AOL worked out their differences a long time ago. Late last year, with Google coming on strong, Microsoft and Yahoo bridged their IM divide. Then Google sank $1 billion for 5 percent of AOL. Where is this heading? Doc Searls may have said it best:
Do you believe a free and open market should be "Your choice of walled garden" or "Your choice of silo"? That's what the big carrier and content companies believe. That's why they're getting ready to fence off the frontiers.