Add meta data to the menu

I encountered this problem what i thought to be one of the worlds simpliest things, I wanted to add a subtitle to the menu somethin alike this http://img4.imageshack.us/img4/7816/unled10b.png . Then i came to realise that the menu doesn’t have its own custom template file, so my plan on loading the page’s meta data namned menudesc didn’t go as planed. I read around alittle and found out that the menu code is found in post-template.php a copied that over to my function file but that didn’t work out either. when i paste wp_page_menu the site goes blanc no errors no nothing, and besides i don’t get how i’m to get the ip for the page inside this function so i can use get_post_meta($page->ID, ‘menudesc’, true);

    function wp_page_menu( $args = array() ) {
    $defaults = array('sort_column' => 'menu_order, post_title', 'menu_class' => 'menu', 'echo' => true, 'link_before' => '', 'link_after' => '');
    $args = wp_parse_args( $args, $defaults );
    $args = apply_filters( 'wp_page_menu_args', $args );

    $menu = '';

    $list_args = $args;

    // Show Home in the menu
    if ( ! empty($args['show_home']) ) {
        if ( true === $args['show_home'] || '1' === $args['show_home'] || 1 === $args['show_home'] )
            $text = __('Home');
        else
            $text = $args['show_home'];
        $class = '';
        if ( is_front_page() && !is_paged() )
            $class = 'class="current_page_item"';
        $menu .= '<li ' . $class . '><a href="' . home_url( '/' ) . '" title="' . esc_attr($text) . '">' . $args['link_before'] . $text . $args['link_after'] . '</a></li>';
        // If the front page is a page, add it to the exclude list
        if (get_option('show_on_front') == 'page') {
            if ( !empty( $list_args['exclude'] ) ) {
                $list_args['exclude'] .= ',';
            } else {
                $list_args['exclude'] = '';
            }
            $list_args['exclude'] .= get_option('page_on_front');
        }
    }

    $list_args['echo'] = false;
    $list_args['title_li'] = '';
    $menu .= str_replace( array( "r", "n", "t" ), '', wp_list_pages($list_args) );

    if ( $menu )
        $menu = '<ul>' . $menu . '</ul>';

    $menu = '<div class="' . esc_attr($args['menu_class']) . '">' . $menu . "</div>n";
    $menu = apply_filters( 'wp_page_menu', $menu, $args );
    if ( $args['echo'] )
        echo $menu;
    else
        return $menu;
}

that’s the code for the menu