Why XAML makes System.Configuration and Enterprise Library Configuration obsolete
It may seem unrelated, but if you haven't read Fowler's article on DSLs (from Google cache if it's down like now), please do so now. It will help you understand why XAML goes far beyond WPF and presentation.
Configuration is typically nothing more than a DSL (external DSL in Fowler's terms) that serves to setup the variable parts of a certain runtime library or framework. For example, while a logging framework has many "static" or invariant components (i.e. logging "pipeline" execution, interaction between components, registration of variable components, etc.), there are variable parts which determine the runtime behavior, such as concrete trace listeners attached to given trace sources, the specific file a file listener will write to, and so on. ...