JRuby 1.7.15 now available
Change effective on 03 September 2014
The Ruby stack now supports JRuby 1.7.15 in 2.0.0 (experimental), 1.9.3, 1.8.7 modes.
To use JRuby 1.7.15 in Ruby 1.9.3 mode, add this to your Gemfile:
ruby '1.9.3', :engine => 'jruby', :engine_version => '1.7.15'
Adjust the ruby value depending on the mode you wish to use.
The JRuby release notes can be found here.