I manage 2 completely separate sites, which both use the Pinboard theme v1.1.0. I have upgraded one site to WordPress 3.6 and am finding that the sub-menu functionality is not working correctly on that site.
If you move the mouse over the “Services” menu on that site, the sub-menu items drop down, but remain dropped-down even after I move the mouse away. I have to actually load another page on the site to get the sub-menu items to disappear.
Scratch that. Must have been something to do with NextGEN Gallery plugin. I had upgraded to NextGEN Gallery v2.0.4 and was having problems, so deleted it, and lo and behold the sub-menu issues with my site disappeared.