Matthew Weier O'Phinney has posted a tutorial to his blog that shows how to implement the dijit.Editor (a dijit helper that didn't make it into the current release of the Zend Framework).
We're getting ready to release Zend Framework 1.6.0. However, one important Dijit had to be omitted from the release as I was not able to get it working in time: dijit.Editor.
This dijit is important as it provides an out-of-the-box WYSIWYG editor that you can use with your forms. Unfortunately, actually using it with forms is pretty tricky -- Dojo actually ends up storing content outside the form, which means you need to create a handler that pulls the content into a hidden element when saving.
He includes the code for a sample view helper to implement it and how to include it into your Zend_Form via an addElement call.