An example chat lobby, where your buddylist is displayed alongside a message log. You can click on another user and send directed private messages to them.
The current example uses a specific social provider that implements a global buddylist, where each user is assigned a random GUID. (source in /providers/social/websocket-server/)
Note that this social provider can be easily replaced by any other that exposes the same Social API. We have drop-in replacements that connect to an XMPP server (such as G+ or Facebook), which the application can then use without any changes to their application code.