This one slipped under my radar, but I figured I should mention it anyway for those unaware. At some point in September, Amazon flipped a switch that enabled Prime Music Stations on the current software version of Fire TVs and Fire TV Sticks. This was not added in conjunction with a software update, but rather just turned on later. My Fire TV running version 18.104.22.168 does not have Prime Music Stations, but my Fire TV running version 22.214.171.124 does, so at some point in between those two version it was added but left disabled until later. Prime Music Stations are similar to radio stations, but you can vote songs up or down to tailor the station to your liking. You can learn more from my overview of the feature when it was added to the Fire OS 5 Developer Preview a few months ago.