Compare post date to cut off date (for layouts)

old-date

<?php 
  $postDate = strtotime( $post->post_date );
  $oldDate = strtotime( '2011-06-29' );
  
  if ( $postDate > $oldDate ) {
  	echo 'do the new thing';
  } else {
  	echo 'do the old thing';
  }