writing a DSL for the .Net platform

I am thinking of writing a DSL to be run in the .Net environment. I am most likely to implement this in C#, though I am flexible on this.

Is there a recommended online resources that show the main steps involved in writing a DSL for the .Net platform?

Ideally, I would like a resource that would provide at least an overview on the following:

• 'Spec'ing a DSL
• How to map the specs to the .Net framework
• Preferably a helloworld example of a trivial DSL implemented in a .Net language

[Edit]

Actually, I have just seen this article - but it is slightly dated. Does anyone have a view on whether the article is a good starting point or not (the .Net framework and C# seem to evolve at a very rapid pace)