I was thinking along the same lines. What happened to Guile ( http://www.gnu.org/software/guile/ )? Maybe the developer(s) were not aware of it's purpose?
Substitute Lua with Tcl and it would still be underwhelming.
Guile is under active development again.
If this is successful, it would not be difficult to make a loader that lets it run Scheme. Of course, there are probably better Scheme implementations than Lua out there.