I'm also trying to do render content from two distinct actions.

Namely one to produce navigation html (based on the request) and one to produce the main content.

As far as I can see the best way to do this is to extend Zend_Controller_Action to automatically forward to another controller, and have all your controllers use this subclass.

I didn't work out how to render the content into a specific section though - all the Zend_Layout tutorials demonstrate the default content placeholder.