This is like dope for all the beta junkies out there. Google just launched the Preview Program for Chromecastâ€¦
Simple answer: You'll be able to test new features on your Chromecast, before they are released to the public. But keep in mind, they may be unstable and are risky to use.
When you registered via the Cast app, you'll get an email with a link, offering you to join the program.
According to Android Police, there isn't any new feature yet, but except some in the near future. Why shouldn't Google use this new program?