Google's casting support has been great if you've wanted to send your phone's videos to your TV, but what about putting music on your speakers? You'll get that option soon. Google has just unveiled Cast for audio, a new spin on the technology that lets you send tunes to networked speakers and receivers. As before, you'll just have to tap a button in a compatible Android, iOS or web app (Google Play Music, Pandora and Rdio are some of the early examples) to get the party started. The audio device itself handles the streaming, so you don't have to leave your mobile gear turned on while you enjoy an hours-long playlist.