Where are Custom Menus saved in the Database for Wordpress 3.0?

Navigation menu items are stored in the wp_posts table with post_type = 'nav_menu_item'.

When new custom menu is added, its entry is added into several tables.

1. table: _term_taxonomy with a column taxonomy and value nav_menu.
2. from 1) term_id is also in table:_terms with the title of menu which is shown in admin panel
3. table:_term_relationship will contain term_texonomy_id from 1) and connection to all object_id which will be linked to all _post table having sub_menu and below level menu.
4. table:_postmeta will contain all the details related to menu and submenu for each object_id from _posts table.