A good article which I though of writing when I started WPF. This describes how dependency property concept is implemented on top of .Net 2.0 framework without even adding a .net language keyword.
http://www.abhisheksur.com/2011/07/internals-of-dependency-property-in-wpf.html
http://www.abhisheksur.com/2011/07/internals-of-dependency-property-in-wpf.html
A MUST read for WPF and Silverlight developers before they actually write code for clients.