Today, Google announced that it's releasing a new beta build of Android Wear, which is only available for the LG Watch Sport. It brings the OS to API 26, which is the same as Android 8.0 Oreo, and it's not a major update. In fact, Google says that this will be the only beta release for this update.
There are a couple of new features though, such as Notification Channels. Users will get "finer-grained control than muting all notifications from the app." You'll be able to choose which notification channels you want to see from the watch itself.
There are also more restrictions on background services. Google says that developers should assume that their app won't run in the background at all without a visible notification.
If you're developing for the OS and you don't have an LG Watch Sport to test it out on, Google says that you can use the emulator that's part of the SDK. If you're using Android Wear for China, there should also be an updated emulator image available.