Last week, LG and Google unveiled the LG Watch Urbane 2nd Edition LTE (pictured above), which became the world's first Android Wear smartwatch to feature cellular connectivity. We're now learning that this is also among the first watches to run Android 6.0 Marshmallow for Android Wear, and that the new version of the OS will be made available to other watches. More exactly, all Android Wear watches released until now (including the very first models from last year: Samsung Gear Live and LG G Watch) will be updated to Android 6.0 Marshmallow.
While the Android 6.0 Marshmallow for Android Wear SDK is already available for developers to download (as API 23), over the air updates for older watches might not be released before the end of the year. According to Google, OTA updates will be rolled out "in the coming months", so for now there's no exact release date.
Among the new things that Marshmallow for Android Wear is bringing, we must mention a new app permissions model, speaker support, and support for Intel x86 processors (the recently released TAG Heuer Connected being the first to use such a processor).
source: Android Developers Blog via Droid-life