Topic: submit_to_remote doesn't do ajax call correctly...?

I have code like this:

<% form_tag do %>
      <td colspan="2"><%= submit_to_remote('get_link', "get link", :url => {:action => 'index'}, :update => 'final_link') %>
      <td><textarea id="final_link"></textarea></td>
<% end %>

Everything is set up correctly, and I can trigger the proper ajax call with link_to_remote. But... somehow remote_form_tag and submit_to_remote both do regular POSTs instead of XmlHttp POSTs. Firebug confirms this, and shows the problem as a javascript error:

$(form) has no properties

I saw something on one of the pages that embedding forms within tables could cause this failure, so I munged things around -- still with no success.

Edge Rails revision          7295

Anyone seen this problem?