Hi Andrey,
yes, IronScheme is the .net based version of the Scheme Lisp language that is runs on the .net runtime and therefore has access to any .net frameworks and libraries (i.e. C#, VB.net)
similar to IronPython, IronRuby et al.
The benefit is that you can have simple text scripts just like autolisp that get read in and 'interpreted' as opposed to being 'loaded'.
This does come with a slight performance penalty as you can call a function say and it would re-read the script in each time the function is called.
BUT
I think it would be possible to cache these functions, this would give you exactly the same performance as a loaded dll.
The real benefit as compared to autolisp is you can use the whole .net framework and the objectARX/BRX .net libraries and develop in a REPL environment, something you can't do at present.