The Zend Developer Zone has lifted the skirt on a new feature in the Zend Framework today with this new article a look at the Zend_Form component, a simple method for creating, validating and generally working with your user's input.
Zend_Form gives you all the tools necessary to create forms and form elements via PHP code. Like everything in Zend Framework, almost everything is configurable; however the defaults are probably good for most uses.
They include some sample code that shows the creation of both a simple, sample form and something a little bit more advanced including validation methods and making fields required.