Microsoft has detailed all of the changes made with DirectX 11.1, and even though there aren't too many worth writing about, there's one new feature that is: native support for stereoscopic 3D. Gone are the days of adding support for 3D based on a particular graphics card, at least as far as DirectX 11.1 is concerned. The problem is that you'll need to be using Windows 8 in order to take advantage of DirectX 11.1.
That's because Microsoft says it doesn't have any plans to make DirectX 11.1 compatible with Windows 7 (or any other version aside from Windows 8 for that matter). "DirectX 11.1 is part of Windows 8, just like DirectX 11 was part of Windows 7," said Daniel Moth on the Microsoft Answers Forum. "DirectX 11 was made available for Vista... but at this point there is no plan for DirectX 11.1 to be made available on Windows 7."
Of course, that might not be a very big deal, as many games we see these days are still based on DirectX 9. Now that there are a large number of Windows 7 machines running DirectX 11, we might see developers begin making more games for that version of DirectX, but it seems that widespread support for DirectX 11.1 is still quite a ways - possibly even years - off. Therefore, if you were planning to upgrade simply because it meant you'd have DirectX 11.1, it's probably okay to wait a bit.
Moth, however, seems to leave the door open when it comes to DirectX 11.1 on Windows 7, saying "at this point" there aren't any plans to retrofit DirectX 11.1 to Windows 7. Those few words seem to suggest that Microsoft might change its mind about DirectX 11.1's exclusivity in the future, but for now, it remains a feature of Windows 8 and Windows 8 only. Keep it tuned here to SlashGear, as we'll have more details for you if Microsoft decides to talk more about DirectX 11.1.