Functional C# - Pattern Matching

In the past, I've covered quite a bit of functional programming in C# 3.0 and how you can implement some of the basic constructs using the language. In preparation for the Richmond Code Camp coming up on October 4th, for which I'm planning to present "Functional C# -or- How I lost the foreach and learned to love LINQ", I'm revisiting some of the topics I've talked about in the past. One of those topics is pattern matching.