title: Rails Facebook-like Notifications
body: <p>In my Rails 3 app I have Users, Products, and Likes. If a User posts a Product, and another User Likes this Product, I want that User to get a notification that their Product was Liked.</p>
  
  <p>Is there an existing gem that handles this? I've only come across Pusher but that seems to be overkill. </p>