After all of the interest shown in the WPF 3.5 SP1 graphics video, I was planning on writing a tutorial showing how to create your own simple custom effect.  Noe need.

Instead, I will point you to Anders Bursjöö Grayscale Effect tutorial.  Anders walks step by step through the process of creating the shader in HLSL, the C# effect class and then implementing the effect in a WPF application.

Nicely done Anders!

For more, Effects goodness, go straight to the source on Greg Schechter's blog.  He's maintaining a list of GPU-based Effects posts which also show how to write custom Effects and explain more detail on how they work.