From http://ruby.railstutorial.org/#new: Fully updated for Rails 3.2 and Ruby 1....

From http://ruby.railstutorial.org/#new:

    Fully updated for Rails 3.2 and Ruby 1.9
    All-new design using Twitter's Bootstrap
    Coverage of the new asset pipeline, including Sprockets & Sass
    Behavior-driven development (BDD) with Capybara & RSpec
    Better automated testing with Guard & Spork
    Roll your own authentication with has_secure_password
    An introduction to Gherkin & Cucumber

I've also converted to a two-pane editor setup using Sublime Text 2, which is especially nice for TDD. See http://youtu.be/REuxSzMtcJA for a sample video.