First I'd like to post answer to the quiz I gave in my previous post: the second snipplet won't compile. The problem is that parameters of type System.Objects are intended to be used for passing boxed instances of primitive types (since there are no compile-time constants of type object), so the metadata format doesn't allow passing null for this kind of parameters.
Also I'm going oo vacation to Germany for two weeks. I plan to write several blogposts about my work in the MPS project. Specifically, I will write about the Collections Language and how it will help developers write effecient and easy-to-understand code.