The Avalon and Indigo Community Technology Preview - March 05 is now available to MSDN subscribers (Tools, Platform Tools, WinFX SDK).
“Avalon” is the code name for Microsoftâ€™s unified presentation subsystem for Windows, consisting of a display engine and a managed-code framework. It unifies how Windows creates, displays, and manipulates documents, media, and user interface, and enables developers and designers to create visually-stunning, differentiated user experiences.
“Indigo” is the code name for Microsoftâ€™s new Service-oriented communications infrastructure built on top of web services protocols. The advanced web service support in “Indigo” provides interoperable secure, reliable, and transacted messaging.