"Avalon" is the code name for the presentation subsystem class libraries in WinFX. Avalon provides the foundation for building applications and high fidelity experiences, blending together application UI, documents, and media content, while exploiting the full power of your computer. The functionality extends to the support for Tablet and other forms of input, a more modern imaging and printing pipeline, accessibility and UI automation infrastructure, data-driven UI and visualization.
Avalon will be available (in 2006) on Windows XP, Windows Server 2003 and all future releases of the Windows operating system.