If you want to make fancy accordion menu on your Drupal site, you can use Accordion Menu module to convert your menu to accordion menu. It will show you menu active states there.

To achieve this, you need to download Accordion Menu from:

http://drupal.org/project/accordion_menu

Because this module is dependent with Jquery UI module, you need to download it from:

http://drupal.org/project/jquery_ui

After you enable both modules on your site, you can go to "Site Configuration -> Accordion Menu Setting". Then you need to select which menu that you want to show as accordion menu.

You can now go to Site Building -> Blocks, then enable your accordion menu. Then you have accordion menu on your site. You need to add your css to get nicer accordion menu.