We (the place I work) are having a debate on if we should move our infrastructure to VM that run ruby instead of default Ruby interpreter that is built natively for different OS. Running Ruby on VM can provide a better security and simplify the upgrading and deployment process. So there is a business case for it. One bad thing about Ruby is that there are a lot of compatibility issues between releases. So that will complicate things more. Anyway, so if we do want to go with running Ruby on VM, then we need to make a decision on JRuby or Rubinius. Rubinius is a Ruby VM that built specificly for Ruby so there is probably some advantage of using it because it will be optimized for Ruby. But Rubinius is still very beta. Recently they just rewrite it in C++ from C. Also there is probably no other language will be running on Rubinius (at least for the near future). So JRuby might be more logical choice because it is more mature and there are many languages now running on java VM. So it seems to me that JRuby will probably a better bet.