rails3 rails.js and jquery catching success and failure of ajax requests

Previously, in rails 2.3.8 i used the prototype-helpers link_to_remote and form_remote_for (amongst others).

These had the option :update as follows:

link_to_remote "Add to cart",
  :url => { :action => "add", :id => product.id },
  :update => { :success => "cart", :failure => "error" }

(an example from the documentation). This example would, upon success update the html-element with class "cart", and upon failure the class "error".

Now i believe the modus operandi has changed, instead we write:

link_to "Add to cart", :url => {:action => "add", :id => product.id}, 
    :remote => true

and there is no option to set :update anymore. Instead of a normal html, we now render javascript, like this (in jquery) :

$('.cart').replaceWith(<%= escape_javascript(render :partial => 'cart') %>)

but how do you handle an error situation? Do i handle it in my controller, and use seperate views?

It would seem useful to me to somehow be able to mimic the behaviour we had before. Any ideas?