I'm having some trouble getting AJAX working properly for me in Rails.  I've 
tried the example in "Agile Web Development with Rails" on page 391 using 
form_remote_tag(), and instead of updating a <div> like it should, it 
renders the form as an entirely new page.  I've tried in on Windows XP and 
OS X 10.4, WEBrick and Apache, using IE and Firefox, and to no avail.

For those who don't have the book, the problem is essentially:

I have a controller with:

def index
end

def blah
    @stuff = 'should print'
    render :partial => 'form'
end


index.rhtml:
<h3>Display me!</h3>
<div id="update_me">
    <%= render(:partial => 'form') %>
</div>

_form.rhtml:
<% if @stuff %>
    <p> <%= @stuff %>
<% end %>

<%= form_remote_tag(:update => "update_me", :url => { :action => :blah } ) 
%>
    blah blah blah
<%= end_form_tag %>

When you submit the form, the <h3>Display me!</h3> part doesn't show again. 
The render :partial => 'form' from the 'blah' action just renders the form 
and doesn't update the "update_me" <div> section.  The WEBrick output is as 
follows:

127.0.0.1 - - [12/Dec/2005:10:43:28 Eastern Standard Time] "GET /guesswhat 
HTTP/1.1" 200 851

- -> /guesswhat

127.0.0.1 - - [12/Dec/2005:10:43:28 Eastern Standard Time] "GET /favicon.ico 
HTTP/1.1" 200 0

- -> /favicon.ico

127.0.0.1 - - [12/Dec/2005:10:43:32 Eastern Standard Time] "POST 
/guesswhat/guess HTTP/1.1" 200 623

http://localhost:3000/guesswhat -> /guesswhat/guess

Notice the difference between the first and third actions:
- -> /guesswhat
http://localhost:3000/guesswhat -> /guesswhat/guess

Does anyone know what the problem is?  I hope this isn't too confusing... 
it's hard to explain.  If you have the book you can run the example yourself 
and see what you encounter.

Thanks in advance,
Charlie