Quick rake task to check if assets need to pre-compiled before deployment (since I don't like precompiling during deployment)

asset.rake

namespace :assets do
  task :check do
    root_dir = File.join(File.dirname(__FILE__),"..","..")
    assets_last_modified_at  = Dir["#{root_dir}/app/assets/**/**"].map { |p| File.mtime(p) }.sort.last
    assets_last_compiled_at =  Dir["#{root_dir}/public/assets/**/**"].map { |p| File.mtime(p) }.sort.last

    if assets_last_modified_at > assets_last_compiled_at
      fail "Assets need to precompiled; last asset modified at #{assets_last_modified_at}"
    end
  end
end

If you're in Rails 3 you can use this: https://github.com/ndbroadbent/turbo-sprockets-rails3