CSS specificity help for deep nested wp_nav_menu() output

[tw2113]

I have a project that has a menu with three children deep menu items. I'm trying to style the grandchildren menu items to only appear on hover, but it's hard to target that ul because it has the same basic "sub-menu" class and no unique ID to help with css specificity. It'd be lovely if some unique identifiers could be added to the output.

[scribu]

Additional identifiers aren't really necessary. Just take a look at the styling of the menu in Twentyeleven. It uses ul ul ul to target specific levels. You could also do ul > li > ul > li etc.