Microsoft has been continuously releasing themes for Windows 7, today Microsoft has released a theme for Windows 8 as well. This theme can work on both Windows 8 developer preview and on Windows 8 consumer preview. The theme is named as Nightfall and Starlight panoramic theme and consists of 9 very beautiful wallpapers. Being Panoramic images these images would extend on both the screens if you are using dual monitors of same resolution. If you are using a single monitor, the central part of the wallpaper is shown.
“Designed to extend seamlessly across dual monitors with identical resolution settings, this dramatic free theme for your Windows 8 Consumer Preview desktop also shifts your glass color to match each stunning, wide-angle image. Explore distant galaxies, verdant meadows, steep mountains, and serene seas without ever leaving your chair”
You can download this wonderful theme from here