Yes, it is true! (Although I haven't seen any anouncement yet; thanks to a friend for telling me.) Google's messaging service, Google Talk, can now communicate with other Jabber servers such as the popular jabber.org. It has always been a Jabber-based system, but its server didn't allow communications with third-party servers before.
I think I'll migrate my account if this one proves to be stable; will be trying it for some days before to make sure :-)