RubyMine is the dedicated Ruby and Ruby on Rails IDE based on IntelliJ IDEA planned for release in April 2009
For more information visit http://www.jetbrains.com/ruby.
RubyMine 1.1.1 is released and available for download and purchase. Visit RubyMine website.
RubyMine 1.1.1 Release Notes
RubyMine 1.1 Release Notes
RubyMine 1.0.5 Release Notes