I don't know how many of you have already seen this but if you want some brain candy check out DSL as in Domain Specific Language. I just met a bright intern who is working on this team and is planning to give a high level overview presentation on September 14th, so if I can make it to his presentation I might be able to report back some more at that time.
From the site: "Using the Microsoft DSL tools you can create your own designer, integrated into Visual Studio, for a visual domain-specific language. The tools help you define the domain-specific language and generate the code of a graphical designer for you. The resulting designer uses the same underlying modeling technology that is used by the Class Designer and Distributed System Designers in Visual Studio 2005."