<?php
	if($post->post_parent)
	$children = wp_list_pages("title_li=&child_of=".$post->post_parent."&echo=0");
	else
	$children = wp_list_pages("title_li=&child_of=".$post->ID."&echo=0");
	if ($children) { ?>
	  <ul>
	  	<?php echo $children; ?>
	  </ul>
<?php } ?>