(1) Introduction of bundler (New way to manage your gem

dependencies)

* (2) Gemfile and Gemfile.lock (Where all your gem

dependencies lies, instead of environment.rb)

* (3) A new .rb file in config/ folder, named as

application.rb (Which has everything that previously

environment.rb had)

* (4) Change in SQL Structure: Model.where(:activated => true)

* (5) All the mailer script will now be in app/mailers

folder, earlier we kept inside app/models.

* (6) Rails3-UJS support. for links and forms to work as

AJAX, instead of writing complex lines of code, we write

:remote => true

* (7) HTML 5 support.

* (8) Changes in the model based validation syntax:

validates :name, :presence => true

* (9) Ability to install

windows/ruby/jruby/development/production specific gems to

Gemfile.

group :production do

gem 'will_paginate'

end