Wes is actually busy with a couple projects so I’m helping him out for a sec. Do you have a link to the site? That’s the only way we’d be able to know if its a plugin or not (a screenshot won’t be enough).
I think it’s a feature that comes standard with the Premise plugin. However, if you don’t have Premise, you can’t have a menu like that unless you tweak the css or use another plugin, many of which look really amateur. Thoughts?