What are Avalon and Indigo, exactly?
Avalon is a graphics subsystem that will help developers build next-generation applications with beautiful user interfaces. Avalon provides two simple programming interfaces: A standard WinFX-based API and an HTML-like markup interface called XAML. Microsoft believes that the introduction of XAML will enable developers to more easily create Windows applications. Indigo is a Web services architecture for providing secure, reliable, transacted messaging between applications and services, whether they reside on the same PC or on different machines, regardless of their physical location. In a simple sense, Indigo is the future of Web services on the Windows platform.