Ruby on Rails 4.0
Fedora 20 includes version 4.0 of the popular Ruby on Rails web framework. This latest release includes improved functionality, speed, and security in addition to better modularization.
Documentation for Ruby on Rails 4.0 can be found at http://weblog.rubyonrails.org/2013/6/25/Rails-4-0-final/ and http://api.rubyonrails.org/ .
Developers moving to Ruby on Rails 4.0 can find assistance from the project's upgrade guide and detailed information in the upstream Release Notes.