only been a few hours since XFastest have released the new GeForce 185.20 beta drivers, including a new release of Nvidia's PhysX engine 8.11.18.
Yet what's particularly noteworthy is that these new drivers contain an Ambient Occlusion setting that can be set to Low
From the description in Nvidia Control Panel:
Ambient Occlusion adds realism to scenes by reducing the intensity of ambient light on surfaces blocked by surrounding objects. It enhances depth perception by providing a soft shadow effect for objects based on their placement in the scene. This feature is not supported for all applications.
Basically, Ambient Occlusion is used to create soft, ambient lighting shadows, emulating diffused lighting such as daylight or indoor ambient lighting. For a more articulate description, refer to the Wikipedia definition here
Additionally, Hardware-Infos has a write-up
comparing GeForce 185.20 beta to several popular drivers releases issued in the second half of 2008.
The drivers are available for Windows XP (32-bit and 64-bit), Windows Vista (32-bit and 64-bit) and Windows 7 build 7000 and can be found here