<span class="post_meta date" title="Posted">
 <b><?php print t('Published'); ?>:</b>
 <span class="metainfo"><?php print date( "M j, Y H:i",$node->created); ?></span>
</span>

<?php if ($node->created <> $node->changed) { ?>

<span class="post_meta date" title="Updated">
 <b><?php print t('Edited'); ?>:</b>
 <span class="metainfo"><?php print date( "M j, Y H:i",$node->changed); ?></span>
</span>

<?php }; ?>