According to Nokia’s update page the Lumia Cyan/WP8.1 update is rolling out to handsets in China, Malaysia and Cambodia.
The update of course brings the new Windows Phone 8.1 features, including the notification centre, VPN and numerous other features, and with Lumia Cyan new imaging improvements and apps.
To see if the update is available to you, go to Settings >Phone updates and check for updates.
via NPU.