This is the "Aero Lite" theme, which comes as a replacement for Windows Basic theme in Windows 8. The "Aerolite.msstyle" file is bundled with Windows 8 by default, but has no proper theme file. Install this themepack, and you will be able to apply Aero Lite theme in Windows 8 RTM. Note that it also disables transparency of the taskbar.
Download Aero Lite RTM theme for Windows 8
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