Windows RT 8.1 Update 3 has been pushed: Win10 start menu in

According to screenshots of foreign Surface RT users on Twitter, Microsoft has already pushed Windows RT 8.1 Update 3. This may be Microsoft's "last concern" for the system users, because Windows RT 8.1 does not support Win10 upgrades.

in this update, similar to an earlier preview version of Windows10 Start menu is added, further improved lock screen. From the screenshot, the user's CPU is NVIDIA Tegra 3, which can be judged as Surface RT.
Both Surface RT and Surface 2 users can download and install this update via the Windows Updater to experience the upgraded Windows RT 8.1 system.