list_pages Question

Hi everybody, I’m using wp function list_pages to show an additional navigation for a specific page and its children.
I’m using the code as follows:

<?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 } ?>

Does anyone knows how to get an ID or Class to the link results of the statement to indicate the current page via css?

Any hint would be appreciated!!! THX !!!