Windows 8 includes an updated “DirectX 11.1 Runtime” that supports Direct3D 11.1, updates Direct2D and DirectWrite, DXGI 1.2, and a revision of the Windows Imaging Component (WIC).
Portions of the “DirectX 11.1 Runtime” are being made available on Windows 7 Service Pack 1 via the Platform Update for Windows 7 Service Pack 1 and Windows Server 2008 R2 Service Pack 1 (KB 2670838) included with Internet Explorer 10 for Windows 7. This includes the updated components above, but is limited to WDDM 1.1 drivers on Windows 7.
Full technical details on what is and is not included in the update are available on MSDN. For information about IE10 compatibility, see this article.
Note: KB 2670838 does not include XINPUT 1.4 or XAudio 2.8 on Windows 7. These remain Windows 8 exclusive. See XINPUT and Windows 8 and XAudio2 and Windows 8 for guidance on handling this difference in Win32 desktop applications.
Update: KB 2670838 and Internet Explorer 10 for Windows 7 are now available. Users with the prerelease version installed should update their systems (DirectX 11.1 and Windows 7 Update).
The updated headers and link libraries needed to target the new components on Windows 8 and Windows 7 are in the Windows 8.x SDK as indicated in previous posts (see Where is the DirectX SDK?). See MSDN for details on ‘mixing’ the Windows 8.x SDK and legacy DirectX SDK if needed.
It is also important to note that the updated “Debug Runtime” components in the Windows 8.x SDK are required on Windows 7 once KB 2670838 is installed. The legacy DirectX SDK (June 2010) “Debug Runtime” for Direct3D 10.x and Direct3D 11.x is not compatible with Windows 8.x or Windows 7 once this update is applied. You can install the Windows 8.x SDK standalone, VS 2012 or VS 2013 which includes the Windows 8.x SDK, or the VS 2013 Remote Debugging Tools (x86 or x64) to get the updated SDK Debug Layers files.
The legacy PIX for Windows tool in the DirectX SDK (June 2010) release does not support Direct3D 10.x or Direct3D 11.x applications on Windows 8, and after this update is applied it will no longer support these applications on Windows 7. Direct3D 9 application debugging continues to function.
Related: DirectX SDK Tools Catalog
Visual Studio 2012’s Graphics Debugger supports Direct3D 11.0 applications on Windows 7 and DirectX 11.x applications on Windows 8. Improved support for KB 2670838 is in VS 2012 Update 2.
When using VS 2012 Update 1's new "v110_xp" Platform Toolset the DirectX 11.1, WIC2, and related headers are not available.