Rails 3.1.0.rc5 setup for heroku with assets pipeline working

application.rb

...
Bundler.require *Rails.groups(:assets) if defined?(Bundler)
...
    # Enable the asset pipeline
    config.assets.enabled = true
    config.assets.precompile << "mobile.css"
    config.sass.load_paths << "#{Gem.loaded_specs['compass'].full_gem_path}/frameworks/compass/stylesheets"
    config.sass.load_paths << "#{Gem.loaded_specs['compass'].full_gem_path}/frameworks/blueprint/stylesheets"

Gemfile

gem 'rails', '3.1.0.rc5'

# Gems used only for assets and not required
# in production environments by default.
group :assets do
  gem 'sass', '3.1.5' # <= downgraded due to a weird interaction b/w compass blueprint and latest Sass
  gem 'sass-rails', "~> 3.1.0.rc"
  gem 'coffee-rails', "~> 3.1.0.rc"
  gem 'uglifier'
  gem 'compass', :git => 'https://github.com/chriseppstein/compass.git', :branch => 'rails31'
end

gem 'jquery-rails'

# UI gems
gem "haml"

production.rb

 # Compress JavaScripts and CSS
  config.assets.compress = true

  # Specify the default JavaScript compressor
  config.assets.js_compressor  = :uglifier

  #<- based on http://devcenter.heroku.com/articles/rails31_heroku_cedar
  config.action_dispatch.x_sendfile_header = nil 

  # Enable serving of images, stylesheets, and javascripts from an asset server
  config.action_controller.asset_host = "xxx-your-xxx.cloudfront.net"