Chrome version 26 stable and Firefox (Nightly build) now support full desktop screen sharing. In Chrome, you have to enable “Enable screen capture support in getUserMedia()” with the chrome://flags URL.
As the desktop screen is treated as a video device, you only have to make a change to the getUserMedia method for video and your existing application will work with no further changes. As an example, I only made the following change to my webrtc video example and now it allows two users to share their desktop screens
navigator.webkitGetUserMedia(
{video:{mandatory: {chromeMediaSource: 'screen'}}},
this.onUserMediaSuccess.bind(this),
this.onUserMediaError.bind(this)
);
To see it in action, just click on this URL https://webrtc.free-solutions.org:8443/webrtc/screen.html from two different PCs. Register with two different user names (no spaces or special characters).
It is hosted by the very good kind and generous folks at free-solutions.org