LOL, i don't think will be ever a PHP parser into Zend Framework.

Reasons:
- there are lot of options in PHP 5, directly as PHP modules: DOM, SimpleXML, XMLReader and so on, and they would work faster than something built in PHP

Check this tutorial about XML options in PHP5 and speed concerns...

- i don't think ZF should replace everything done before over PHP platform

Personally i am using SimpleXML, because of simplicity, combined with XPath is great to solve lot of problems...

Mmm, this post make me think about adding maybe an additional resource section, for third party tools which are good to be used with ZF, to work together...