Ruby on Rails (ROR) is Ruby programming language web framework for developing online applications for the world wide web (the Internet). It follows the MVC (Model View Controller pattern) for development of web applications. It is not popular as other programming languages but there are good number of developers who develop apps. Popular websites use Rails including: twitter.com (microblogging service), scribd.com (document-sharing website), github and many others.
Hostgator Ruby on Rails
Hostgator supports ROR on all its shared and reseller servers. The latest version (currently installed) is:
Ruby Version : ruby 1.8.6 (2008-03-03 patchlevel 114) [i686-linux]
Gem Version : 1.0.1
Rails Version : Rails 2.0.2
Ruby on Gator it comes with the following gems preinstalled: actionmailer, actionpack, actionwebservice, activerecord, activesupport, bluecloth, builder, daemons, feedtools, gemplugin, gnuplot, htmltools, mongrel, mysql, payment, rake, sources, tidy, uuidtools, xml-simple and others. Refer to this forum post for more: http://forums.hostgator.com/ruby-rails-support-t13038.html
You will need SSH access to develop Ruby applications. Visit
https://secure.hostgator.com/sshrequest.php for more info on enabling SSH access on your account. You may also want to enable SVN (Subversion), you submitting a ticket.