Emberjs < 1.0 with Rails 3+

The safest bet is to use the ember-rails gem and require the ember and ember-data in application.js

//= require ember
//= require ember-data

In addition to this though with ember-rails -v 0.6.0 you'll have to add the following to your environment config files

in development.rb

config.ember.variant = :development 

in production.rb

config.ember.variant = :production

in test.rb

config.ember.variant = :test

A sample of an ember app working within Rails 3.2 can be found at:

http://github.com/mehulkar/teams