The built-in assistive technologies in Windows 8 work with both Windows 8 applications and with desktop software to provide seamless access to the entire Windows experience.
Details here.

This 88 page word document provides an overview of Accessibility in Windows 8 including What’s New in Windows 8 Accessibility, Ease of Access, Personalization, Mouse and Keyboard, Keyboard Shortcuts. You can get details here: Download Windows 8 Accessibility Tutorial Guide.