Easily get Backbone.js and its dependencies into your app.

Rails 3.1

BAM!

//= require json2
//= require underscore
//= require backbone

Minified?

//= require underscore-min
//= require backbone-min

Rails 3.0

Slightly quieter BAM!

rails g backbone:install

You'll get these:

public/javascripts/json2.js
public/javascripts/underscore.js
public/javascripts/underscore-min.js
public/javascripts/backbone.js
public/javascripts/backbone-min.js

The version number of the gem is the same as the version number of Backbone, plus an extra version number to handle minor Gem updates.