Microsoft are releasing more and more information about Windows 8 every week, This time they are talking about the new accessibility features that will be included. The idea behind this is to include more control over Windows by adding different way to control it in the first place. Microsoft have gone as far as to make it a more app building inclusion, Meaning those bulding new applications for Windows 8 can test out functionatly with the new accessbility features within the SDK, They have a also released a video about it(Below) explaining the purpose and execution of the new features. Also check out the source for more information.
Source: MSDN Blog