Today, Google launched the developer preview for Android 8.1 Oreo, for those that have a Nexus 5X, or later. It's basically a sneak peak at what the Android team has been working on. Since this is a .1 update for Android Oreo, it is mostly full of small tweaks to features that were launched in Android 8.0 Oreo, with some changes to the API's and such. But Google has explained exactly what is new with Android 8.1 Oreo, including some changes for Android Go.
With Android Go, this developer preview includes a set of memory optimizations for Android Go configurations. The Android team has also added some new hardware feature constants, allowing you to target the distribution of apps and APK splits to normal or low-RAM devices that are running Android 8.1 or later. In the NDK, Google did add a Neural Networks API to Android 8.1, which is going to allow Google to use Neural Networks in more parts of the operating system. Google has also made it easier for apps to use the autofill framework that debuted in Android 8.0 Oreo, instead of having to go through Accessibility options (and essentially hacking the operating system) to do autofilling, this mostly applies to password management apps like Lastpass. Google has also added the Shared Memory API. This API allows apps to allocate shared memory for faster access to common data. Which will make things much easier for those that have slower or older devices.
Google also noted that the API's for API level 27 are final. That means that developers are able to develop apps for Android 8.1 and use these new API's and also publish to the Play Store now. That's different from the previews for Android 8.0 Oreo, which was a larger update and had much more "beta" previews than Android 8.1 is having, which resulted in API's changing based on feedback from users and developers using the preview and such. Google expects that Android 8.1 Oreo should begin rolling out in December as a stable update for the Nexus 5X, Nexus 6P, Pixel, Pixel XL, Pixel C, Pixel 2 and Pixel 2 XL. Partners do have the code for Android 8.1 Oreo, but don't expect to see it launch for other devices until 2018.