show me more than the post really in the current category

if ( is_single() ) {  
  $cats = wp_get_post_categories($post->ID); 
     if ($cats) {      $first_cat = $cats[0];  
    $args=array(        'cat' => $first_cat, //cat__not_in wouldn't work 
       'post__not_in' => array($post->ID),        'showposts'=>5,   
     'caller_get_posts'=>1      );      $my_query = new WP_Query($args);  
    if( $my_query->have_posts() ) {        echo 'Related Posts';  
      while ($my_query->have_posts()) : $my_query->the_post(); ?>   
       <p><a href="<?php the_permalink() ?>" rel="bookmark" title="Permanent Link to <?php the_title_attribute(); ?>">
<?php the_title(); ?></a></p>   
      <?php        endwhile;      } //if ($my_query)    } //if ($cats) 
   wp_reset_query();  // Restore global post data stomped by the_post(). 
 } //if (is_single()) 
 ?>

More--->
http://wordpress.org/support/topic/310930