As it turns out, Spotify isn't the only music app that can control Sonos connected speaker systems. Google Play Music can as well.
Recent Google Play Music Stories
Google Play Music for Android, iOS and the web is getting a major refresh, with a new user experience and new personalization capabilities.
This was one of those long-running open secrets, but now it's finally happening: Google has added podcast support to its Google Play Music service. And, Google being Google, they are of course doing it in their own quirky way.
Google announced this morning that it will now offer a free, ad-supported version of its Google Play Music streaming music service that works like radio.