I’d love for my PMS to support the Sonos API (http://musicpartners.sonos.com/?q=docs) which would allow me to broadcast music to all my sonos devices. (Bonus points if it could include mirrored sound of video content as well)
The Plex interface is far superior to the one Sonos has. I want Plex to be my single interface for all media. Having Plex control Sonos speakers directly would be a huge win.
+1 I would love this. Nobody wants to have the awesome Plex interface at their fingertips whil being forced to use the aweful Sonos one. 
Early 2021 clean-up: implemented
