WDDX seams to be an unpopular standard and kind of dead. I had trouble finding 
usable docs about it. Is there a substitute? If so, is there PHP function for it?
I don't think that following has a high priority but it would be good if you at 
least could have a look at following <dataTime> problem. 

It's not mentioned which version of WDDX PHP is using, but the current implementation 
ignores some tags that have been in WDDX since V0.9 (1998). 
- PHP just ignore(!) the <dataTime>-tag. 
  Couldn't you at least transform it to a string instead of just dumping it?

- Also <recordset> is not supported. I get a funny result.

For a WDDX DTD V=0.9 (1998) See: http://www.macromedia.com/v1/documents/objects/whitepapers/wddx_dtd.txt

The PHP sample:

<?php
$wddx =<<<EOD
<wddxPacket version='0.9'>
  <header/>
  <data>
    <struct>
    
      <var name='dateTime'>
        <dateTime>1998-06-12T04:32:12</dateTime>
      </var>
      
      <var name='recSet'>
        <recordset rowCount='2' fieldNames='NAME,AGE'>
          <field name='NAME'>
           <string>John Doe</string>
           <string>Jane Doe</string>
          </field>
          <field name='AGE'>
           <number>34</number>
           <number>31</number>
          </field>
        </recordset>
      </var>
      
    </struct>
  </data>
</wddxPacket>
EOD;

$des = wddx_deserialize($wddx);
echo "<pre>";
var_dump($des);
echo "</pre>";
?>