Also in testing a few weeks ago, since the release of its official version 11, the tvOS has just been updated for the 11.1 (compilation 15J582).
This is the operating system of the two most recent versions of set-top box da Ma, the fourth generation (launched in 2015) and the recently launched Apple TV 4K that started selling in Brazil recently.
So far, we don't have exact information on what's new for Apple TVs, but we will update this article when we know. In general, we can expect clear general improvements and bug fixes.
TvOS 11.1 can be installed by opening the Settings app on Apple TV, and then going to System Software Update.
Update 10/31/2017 s 18:40
For those interested, here is the support article with all the security fixes for tvOS 11.1.