The good news is, been there, done that. The less good news is that you got the technical story sort of backwards.

The functional quality of gchat (not an official Google service name: it's the text messaging component of the text and voice messaging service called Google Talk) that you like, the "I see who is on when I arrive" element, has been part of "instant messaging" or "chat" programs since the beginning.

For our purposes, the beginning was free software. The service called IRC, or Internet Relay Chat, predates the Web, is almost as old as News, and just somewhat younger than the concept of email. IRC is a complexly-federated service, with tens of thousands of servers, dozens of relay networks, and an extremely large number of different free software programs that provide access to its protocols. It's more secure than the "instant messaging" systems that copied from it, and has more features. Services like the chat part of Google Talk, AOL Instant Messager, Skype Chat, and so on are just degenerate, centralized versions of IRC.

But Google Talk is built on top of a much more sophisticated messaging protocol, XMPP, which is free, and primarily implemented in free software. XMPP is a "presence" protocol (there's the part you like), which can transmit text, voice, video, or any other form of bits in a many-to-many geometry, efficiently. The future of Internet telephony isn't Skype, it's the Jingle standard, which is an XMPP representation, to which Google is converging Google Talk.

FreedomBox contains a complete, secure XMPP messaging platform in its 1.0 version. This is the easiest part of the task for us to complete. Because we already have dozens of FOSS applications for XMPP chat, including our multi-protocol chat client, Pidgin, which can connect you to your "Gchat" friends and your AIM friends and your IRC chatrooms and any other XMPP servers anywhere on the planet you care to connect through, with conversation security, all at once. So all we have to do is make them more secure on a network that can be trusted to have only your actual, real friends on it no matter who is trying to listen in between. So later this year you will have a real, secure, effective system of text, voice and video chat compatible with "Gchat" architecturally "built-in" to any FreedomBox computer.

That's the good news. The bad news is that you didn't know any of this, though a few hours with the Wikipedia would have done wonders in carrying you from "Gchat" all the way to FreedomBox. I think the next revision has to take a little more account of the factual context.