As of Genesis 2.1, the Primary Navigation Extras options have been removed for new installs. (upgrades of current installs to 2.1 will not lose the Primary Navigation Extras settings). If you are running a new install and want to add a the date or a search form to a navigation menu, use the following code. (see comments for further instruction)
Note: CSS Styling may be required when adding Navigation Extras and will be dependent on your theme. Any changes you wish to make to Navigation Extra display can be made to your child theme style.css file. We highly recommend using Firebug.