http://exviva.posterous.com/upgrading-a-rails-3-beta-4-application-to-rai

gistfile1.diff

Rakefile
-Rails::Application.load_tasks
+My::Application.load_tasks


config/application.rb
-Bundler.require :default, Rails.env
+Bundler.require(:default, Rails.env) if defined?(Bundler)

-    # config.load_paths += %W( #{config.root}/extras )
+    config.autoload_paths += %W( #{config.root}/lib )
+    # config.action_view.javascript_expansions[:defaults] = %w(jquery rails)
+    config.encoding = "utf-8"

-    config.filter_parameters << :password
+    config.filter_parameters += [:password]


config/boot.rb
+require 'rubygems'
+gemfile = File.expand_path('../../Gemfile', __FILE__)

-  require File.expand_path('../../.bundle/environment', __FILE__)
-rescue LoadError
-  require 'rubygems'
+  ENV['BUNDLE_GEMFILE'] = gemfile
+rescue Bundler::GemNotFound => e
+  STDERR.puts e.message
+  STDERR.puts "Try running `bundle install`."
+  exit!
+end if File.exist?(gemfile)


config/environments/development.rb
+  config.active_support.deprecation = :log


config/environments/production.rb
+  # Specifies the header that your server uses for sending files
+  config.action_dispatch.x_sendfile_header = "X-Sendfile"
+
+  # For nginx:
+  # config.action_dispatch.x_sendfile_header = 'X-Accel-Redirect'
+
+  # If you have no front-end server that supports something like X-Sendfile,
+  # just comment this out and Rails will serve the files

+  config.i18n.fallbacks = true
+  config.active_support.deprecation = :notify


config/environments/test.rb
+  config.action_dispatch.show_exceptions = false
+  config.active_support.deprecation = :stderr


config/initializers/secret_token.rb
-Rails.application.config.secret_token = '(...)'
+My::Application.config.secret_token = '(...)'


config/initializers/session_store.rb
-Rails.application.config.session_store :cookie_store, :key => '_my_session'
+My::Application.config.session_store :cookie_store, :key => '_my_session'


config/routes.rb
-My::Application.routes.draw do |map|
+My::Application.routes.draw do