I followed one of the myriad links to Stevey's Blog Rants for the Rhino on Rails explanation (long story short: for the rest of us, JRuby on Rails or Grails probably makes much more sense, even if the project wasn't internal at this point). On the other hand, if it leads to enhancing/updating Rhino, go for it, guys!
I was a little tickled by a different entry on Rich Programmer Food (or, "Why Stevey thinks programmers should be at least familiar with how actual compilers work"). Stevey gleefully pokes fun at C++, Java, and Perl as a matter of course (especially Java--have you read about the Kingdom of Nouns?). But do you suppose he knows that part of Perl 6's design is the ability to write grammars? Moreover, the Parrot work has led to a set of tools that make implementing languages for Parrot easier. Compiler theory and DSLs, indeed!