Isn't Guile going to be integrated with Emacs at some point? I thought the work has already been completed so Guile can run elisp as well. If Emacs devs could switch to Scheme (Guile) while having backward compatibility with elisp then a lot of cool stuff could be written in Emacs that can't be done now for performance reasons.

I've also heard of plans to from C+elispvm to Guile Scheme + elisp compatibility, but at least some Emacs people seem to be against it. Try asking in #emacs