<?php
$m_items = _menu_get_active_trail();     // get active menu trail into an array
$m_item = $m_items[1];                           // the second entry is the top parent (assumes we have one main menu container, e.g. primary links)
print menu_item_link($m_item);               // this function takes the menu id (mid, which is $m_item) and creates a link to the page

$link_array = menu_item_link($m_item, FALSE); // this gets the menu item into an array
print 'Title:' . $link_array['title'];

// you can therefore add the section to the css by doing this:
// $body_classes[] = $link_array['title'];
?>