I too had the same issue some people were having here with their dropdown no longer working. It appears the recent version of dropdown and WordPress don't play nicely, and it doesn't seem to pick up the hoverIntent.js file which the plugin needs to display the dropdown.
So my temporary fix which worked for me was to simply point to the hoverIntent.js file in the head of my site, after loading the most recent version of JQuery:
<!-- JQUERY LOAD -->
This seems to get the plugin working again. I have looked in the core .php file and although I can see the point it loads in the hoverIntent.js file, it makes no difference.
Not the best fix I admit, it's a sticking plaster. But better to have it than not having a dropdown working.