Has anybody been thinking about Microsoft's DLR? It will be part of Silverlight. Lua sounds like an excellent language for this kind of thing. Imagine Flash on steroids with Lua in place of clunky ActionScript!
Of course, this might require a complete re-implementation of the language. Also, Lua generally prides itself in being small, self-contained, pure C, etc, etc. Still, I think it is intriguing…
Here are some links: