http://drupal.org/sandbox/x7ian/1996698
It's one of the better solutions I've seen to date, for dealing with mutliple-level dropdowns.
There's a great example here - http://liceochapero.edu.gt/ - if you reduce the width of your browser
The module has some nice configuration options.
There's currently no active menu action :)
Meaning, if I'm on a third-level page, and toggle the menu, it always starts from the top level.