It was promised for 21st December, but Sonos has delivered early, confirming that the update is rolling out. If you're set to receive notifications about updates, you might have already got it.
Previously, Alexa support only worked with some services like Amazon Music, but now you can also ask an Echo to play songs from Spotify on any of your Sonos speakers, or ask the Sonos One to play your music from Spotify.
It should all work as long as you set Spotify as your default music service in the Alexa app on your smartphone or tablet.
There's more good news for Sonos fans too: the Sonos Play:1 is currently discounted at Amazon UK, meaning it's even cheaper to expand your Sonos system.