This sounds like a good idea, but (1) as a # user, I don't think the protocol or the implementing software are "ready for prime time" and (2) I don't see any sign that they have given much thought to NAT, firewalls, or DNS. An organization, once it has sufficient internally technology resources, could quickly get this working, but that sized org is just as likely to buy a real server and run their own chat & IM service (or contract it out to any of the "enterprise" vendors).

I think this targets home users and really small businesses without an IT background and should probably include (and talk about) some tools and services to make that use case realistic.