
You can download the plugin on https://github.com/gerard33/sonos. Instructions on how to setup and use the plugin are also there.
Short overview of the functions:
* Shows the [artist] - [song] or [radiostation] - [song] being played
* Change the volume or (un)mute
* You can choose between the following icons: Sonos logo, Sonos 1, Sonos 5
* You can send notifications to the Sonos which will trigger an mp3 file to be played on the Sonos, after that the Sonos will continue playing the song/radio station which was played before that notification
* A selector switch with a maximum of 10 radio favorites from your Sonos (from the My Radio Stations of Radio by TuneIn) is available. When a radio station from this list, which is not selected this Domoticz switch (e.g. from your Sonos app), is playing then this switch will be updated with that radio station.
* On/off, previous/next and pause buttons.
There are still some things I need to do (replace the sleep solution in the onNotification function with another solution, some code cleanup), but the plugin is ready for testing.
I have tested this plugin succesfully with the latest Domoticz stable v3.8153 on Ubuntu Server 14.04.
Nevertheless there still seem to be some issues with Python plugins which run on precompiled Raspberry Pi versions of Domoticz. See this topic.
If you have an error message like in that topic (Error: Domoticz received fatal signal...) then there is nothing I can do about that in the plugin.
Please let me know if you have any issues (other then the issue mentioned above) with the plugin or any features you would like to add.
If you use the plugin satisfactorily then please let me know that by making a short post in this topic.
It's always good to know that there are happy users

Many thanks to tester22 for developing the first version of the plugin! Without his work I would have never been able to make this updated version of the plugin.