XAML is just plain awesome. XAML will allow you to configure the user interfaces of you applications using an XML based language. Just think of how easy it is to create a web interface with HTML, and that is how XAML will be for Windows applications. It's just too bad that it wont be supported by Windows until Longhorn ships. I can't wait to start using it.
The following example demonstrates that all you need to do to write a "Hello World" application in XML is to initialize a window class and add a button with text.:
<?xml version="1.0" standalone="yes"?>
Go to the following link to read more about XAML: http://longhorn.msdn.microsoft.com/?//longhorn.msdn.microsoft.com/lhsdk/core/overviews/about%20xaml.aspx