The latest DirectX version, 11.1 will not be available to users of Windows 7, marking an acceleration of the strategy that Microsoft used with Vista and DirectX 10.
DirectX11.1's notable feature is the native support of stereoscopic 3D, but other refinements populate the functionality list released by Microsoft
In the associated gamesindustry International article, principal program manager lead for Microsoft is quotes as saying, "at this point there is no plan for DirectX 11.1 to be made available on Windows 7.”
The article concludes by referencing one number from Steam's Hardware & Software survey for October 2012, that being the 50.89 percent of respondents who currently use both Windows 7 and a Direct X 11 GPU, the very group most primed for added DirectX functionality.
Source: gamesindustry International