prototype-rails provides Prototype, Scriptaculous, and RJS for Rails 3.1.

Prototype and Scriptaculous are provided via the asset pipeline and you
do *not* need to copy their files into your application. Rails will get
them from prototype-rails automatically.

You may want to add them to your app/assets/javascripts/application.js:

    //= require prototype
    //= require prototype_ujs
    //= require effects
    //= require dragdrop
    //= require controls

New applications using this may also want to add

    config.action_view.debug_rjs = true

to their config/environments/development.rb.