WordPress version: 3.1.3
Parent theme: TwentyTen 1.2

Add a horizontal footer menu to child theme (since Twenty Ten parent theme doesn’t have it as a default).

Instructions from: Digging into WordPress – Using Menus in WordPress 3.0

In addition to the above instructions, add CSS and array controls from the main menu:

File: footer.php (in child theme folder)

<div id="access" role="navigation">
<?php wp_nav_menu( array( 'container_class' => 'menu-header', 'menu' => 'Footer menu' )); ?>
</div>