Rinari Is Not A Ruby IDE.

Well, ok it kind of is. Rinari is an Emacs minor mode that is aimed
towards making Emacs into a top-notch Ruby and Rails development
environment.

IMPORTANT NOTE: This package is unmaintained these days, and
users should consider an alternative, e.g. the projectile-rails package.

For a screencast of Rinari see
http://vimeo.com/2854412

For the latest version see
http://github.com/eschulte/rinari/tree/master

For somewhat outdated installation instructions and documentation see
http://rinari.rubyforge.org

For discussion of Ruby on Rails related Emacs development see
http://groups.google.com/group/emacs-on-rails