You may have noticed when using Windows 8 how the graphics seem to have more clarity and just generally look better. This is down to something called WDDM 1.2:
The Windows Display Driver Model or WDDM for short allows Microsoft and GPU devs to add new features whilst also making better use of the available power. It's this software (along with hardware developments) that has really brought the GPU to where it is today.
WDDM 1.2 which is included with Windows 8 allows support DX 11.1 as well as a whole raft of features.

In addition to the above Microsoft has a downloadable PDF which is available here:
Windows Display Driver Model Enhancements in Windows Developer Preview
The tech site AnandTech has also produced article concerning WDDM 1.2 and can be found here:
AnandTech - In-Depth with the Windows 8 Consumer Preview
WDDM v1.2 is required for all systems shipped with Windows 8. WDDM v1.0 and WDDM v1.1 will continue to work on Windows 8. However, the best experience and Windows 8–specific features are enabled only by a WDDM v1.2 driver.
The Windows Display Driver Model or WDDM for short allows Microsoft and GPU devs to add new features whilst also making better use of the available power. It's this software (along with hardware developments) that has really brought the GPU to where it is today.
WDDM 1.2 which is included with Windows 8 allows support DX 11.1 as well as a whole raft of features.

In addition to the above Microsoft has a downloadable PDF which is available here:
Windows Display Driver Model Enhancements in Windows Developer Preview
The tech site AnandTech has also produced article concerning WDDM 1.2 and can be found here:
AnandTech - In-Depth with the Windows 8 Consumer Preview