From Slashdot: Google has recently released Google Talk, an IM service running on the Jabber/XMPP protocol (which means anyone can connect to the service using their favorite open source client). According to their helpful developer pages, they plan to provide federated service and are in talks with Sipphone and Earthlink. The protocol they are using to carry VoIP is still under wraps, but they are planning to document it and open it up to allow other IM clients to support VoIP.
Coolness!
Previously: On The Flipside: Why Low-level Languages May Be A Win