form_remote_for & file uploads

Has anyone successfully gotten Ajax file uploads working using
form_remote_for & attachment_fu? I have seen Sean Treadway's
responds_to_parent plugin and many other samples available, and they
all seen to statically generate <form> tags. Is there a way to get a
file upload to work using the Rails helpers?

<% form_remote_for(:message, @message, :url =>
contacts_messages_path(contact), :method => :post, :html =>
{:multipart => :true, :id => "new_message_form", :target => "frame"})
do |f| %>
<iframe id='frame' name="frame" style="display:none;"></iframe>
...fields...
<% end %>

Help is appreciated.

- j