Using menu_minipanel module to create an editor-manageable mega-menu

Here's the effect we are building. The site pictured is entirely unthemed so far (based on Acquia Marina for now), we have imported a lot of the content and are now doing the structure. The visual polishing will come later.

The feature request is for some managed mega-menus, with arbitrary rich editor-managed content to come up as part of the top-level menu.

A normal hierarchical menu manages most of the content structure, and we will provide a drop-down to list the second level items, and more.