Does anybody out there know of any Groovy-like languages currently being developed for the CLR?

As much as I love working on Sencha, I'm coming to the point where some of the more esoteric features of Scheme are beginning to surface. (Read: more time consuming and difficult to implement.) These include macros, continuations, and all of the proper edge cases of tail calls. I intend to invest further in the project, but have begun to think about other related efforts a bit more realistically. I'm at the point where I can almost compile all R5RS compliant syntax minus the aforementioned challenges, and the amount of midnight oil I have left to expend is pretty limited at this point. I need to invest it wisely.

In particular, I'm interesting in developing a language which is a mini-superset of C#. It's a bit odd to say "mini" and "superset" at the same time, but I'm thinking of starting out initially by paring away languages features (e.g. making all type annotations optional--relying on inferencing where possible and dynamic typing otherwise, relaxation of namespace declarations (i.e. "using" and auto-searching linked assemblies, reporting error upon resolution failure), runtime interpretation and execution) and then extending it with some interesting facets (e.g. non-delegate based closures, declarative concurrency, structural typing, more inferencing all over the place in addition to namespace declarations and typing (main method loops, and so on), plus more).

I've already found a name for it. C♭ (pronounced "see flat").

Any thoughts or input on such an effort would be apprciated. Ciao.