Avalon, Indigo and WinFX

Avalon, Indigo and WinFX, Microsoft introduce these technologies as "The Pillars of Vista". New structure of the operating system includes the .NET framework, an application deployment engine, improvements to the installation of applications (Windows Installer/MSI 4.0) etc.
These are the definitions for these terms as in Wikipedia.
Avalon: a new user interface subsystem and API based on XML, .NET, and vector graphics, which will make use of 3D computer graphics hardware and Direct3D technologies.
Indigo: a service-oriented messaging system to allow programs to interoperate as part of the .NET framework.
WinFX: a new API to allow access to these new features, replacing the current "Win32" API (see Windows API).