What Is The Best Way To Upload A Bunch Of Items At Once?

I've been looking for several days at examples of using a flash file uploader. I was after single or multiple file uploads, a progress bar and the ability to add "vanilla" form fields. The most promising I found was the YUI uploader from those nice people at Yahoo http://developer.yahoo.com/yui/examples/uploader/u...

I got it working fine submitting to a simple CF page

<cfif structkeyexists(form,"Filedata")>
<cffile action="UPLOAD" filefield="Filedata" destination="#expandpath(".")#" nameconflict="OVERWRITE">
</cfif>

<cfif structkeyexists(form,"var1") and structkeyexists(form,"var2")>
<cffile action = "append" file = "#expandpath(".")#\log.txt" output = "var1 = #var1# var2 = #var2#">
</cfif>

I'm a complete novice with Javascript, PHP, flash in fact anything other than CF, so there's a bit I don't understand (well several ... but this one in particular!)

On the example in the YUI documentation they say they are using this PHP scrip to handle server side

1 <?php
2 foreach ($_FILES as $fieldName => $file) {
3 move_uploaded_file($file['tmp_name'], "./" . $file['name']);
4 echo (" ");
5 } ?>

The echo bit seems to "bounce back" the post data which is then picked up by the onuploadresponse(event). In CF how would I pass back some response to the calling page to fire this event?