At the Surface Event, Microsoft confirmed the RTM build of Windows 10 October Update following which the update was made available for the public. While Microsoft has planned a phased rollout, users have started getting the October Update.
One of the highlighted features of the new update is Your Phone. The app will allow users to sync their Notifications (under development), Messages and Photos directly from Android/iOS to Windows 10 PC. This will allow them to transfer photos or send messages without touching their smartphones. The feature looks to be a hit as Your Phone Companion App is #1 trending app on the Google Play Store.
This to me is the highlight of 1809.