See also the original announcement of the 2nd Edition, which includes a FAQ and a list of new features:

http://news.railstutorial.org/ruby-on-rails-tutorial-second-...

The biggest changes are:

    * A full update to Rails 3.2, including coverage of the
      asset pipeline

    * A complete rewrite of the authentication & authorization
      system, taking advantage of the new has_secure_password method

    * A revised test suite using the latest techniques in
      RSpec programming