Rails-3-App-Template.rb

# create fresh git repo
git :init
git :add    => '.'
git :commit => '-a -m "fresh rails app"'

# include gems
gem 'rspec',          '>= 2.0.0.beta.19', :group => :test
gem 'rspec-rails',    '>= 2.0.0.beta.19', :group => :test
gem 'cucumber',       '>= 0.8.5',         :group => :test
gem 'cucumber-rails', '>= 0.3.2',         :group => :test
gem 'webrat',                             :group => :test

# run cucumber and rspec generators
generate 'rspec:install'
generate 'cucumber:install --rspec --webrat'

# create rspec.rb in the config/initializers directory to use rspec as the default test framework
initializer 'rspec.rb', <<-EOF
  Rails.application.config.generators.test_framework :rspec
EOF

# download latest unobtrusive rails adapter for jquery 
get 'http://github.com/rails/jquery-ujs/raw/master/src/rails.js', 'public/javascripts/rails.js'

# create jquery.rb in the config/initializers directory to use jquery as the default javascript framework
initializer 'jquery.rb', <<-EOF
  Rails.application.config.action_view.javascript_expansions[:defaults] = %w(http://ajax.googleapis.com/ajax/libs/jquery/1.4.2/jquery.min.js rails)
EOF

# commit template results to repo
git :commit => '-a -m "applied application template"'

Check out http://refactored.tumblr.com/post/953522976/rails-3-getting-started-part-3-application-templates for how this is used.