The Chromecast dongle is plugged into a TV, and can then be auto-discovered by apps like the YouTube app on a mobile device. Users can then change the volume, start immediate playback and compile collaborative playlists. This is essentially the same functionality that’s been available on Google TV for some time, but without the whole Google TV UI.
Chromecast works with both Android and iOS devices as well as laptops running Chrome, and can be used from within multiple apps, including YouTube, Google Play Movies and Netflix. It’s also supported within Google Play Music and Pandora for music playback. Users can even start streaming photo slideshows straight from within Chrome.
Google will make the same functionality available to other app developers through a Google Cast SDK. Also, Chromecast is just a first device to make this available, but Google wants to bring the same functionality available to partner devices.
The Chromecast dongle will sell for $35, according to the Google Play store, which states that it is shipping within 1-2 days.
Update: The Verge has a comparison of Chromecast and Apple’s AirPlay.