A recent tutorial (screencast) has been posted to the ZendCasts.com site looking at creating custom Zend_Form elements when you need something more than just the usual, simple elements.
This video should help you build your own composite Zend_Form element. We'll be building a phone element. The phone element will have 3 textboxes, one for geographic location, area code and local code. In the following videos will add a custom cell phone validator and some ajax validation.