Horizontal tree-like menus in Pixel Clever Tutorials | Pixel Clever

I would like to implement a menu system like the one in the top block of the main column in the Pixel Clever tutorials section, in which two horizontal menus at the bottom of the block seem to do duty for a menu tree, with the selected results (taxonomies?) being displayed on the blue menu bar at the top.

This is really great work in my humble opinion. If any how-to sharing is possible and appropriate, I would be most appreciative.