I like the idea. There's also some sort of Zeroconf-based chat in Pidgin/Telepathy/Empathy which serves the same purpose and doesn't rely on you and the Intern

I like the idea. There's also some sort of Zeroconf-based chat in Pidgin/Telepathy/Empathy which serves the same purpose and doesn't rely on you and the Internet for privacy, although it isn't quite as instant as your solution.