WebRTC lets you build peer-to-peer communication into a browser application.
Establishing the connection
The initial connection between peers must be accomplished via an application server that provides for user discovery, communication, and Network Address Translation (NAT) with data streaming.
Signalling is the mechanism by which peers send control messages to each other for the purpose of establishing the communication protocol, channel, and method. These are not specified in the WebRTC standard. Rather, the developer may choose any messaging protocol (such as SIP or XMPP), and any two-way communication channel (such as WebSocket or XMLHttpRequest) in tandem with a persistent connection server API (like the Google Channel API) for AppEngine.
WebRTC support in Firefox is hidden behind a preference switch. Go to about:config and set 'media.navigator.enabled' to 'true'.
There are some test files in the source tree to give you an idea what things work. See: dom/media/tests/local_video_test.html. Please also try the call service demo, its page source, and its server source.