posts with same tag of last post of current user

<?php
//display posts authored by the logged in user
if ( is_user_logged_in() ) {
  global $current_user;
  get_currentuserinfo();

  $args=array(
    'author' => $current_user->ID,
    'post_type' => 'post',
    'post_status' => 'publish, private'
 );

 global $post;
query_posts ('cat=1 &posts_per_page=1'); ?>
<div class="post" id="post-<?php the_ID(); ?>">

<?php
//for use in the loop, list post titles related to first tag on current post
$tags = wp_get_post_tags($post->ID);
if ($tags) {
  echo '';
  $first_tag = $tags[0]->term_id;
  $args=array(
    'tag__in' => array($first_tag),
    'showposts'=>-1,
    'caller_get_posts'=>1
 );
$my_query = new WP_Query();

 if( $my_query->have_posts() )
{
    while ($my_query->have_posts()) : $my_query->the_post(); ?>

<ul>

<a href="<?php the_permalink(); ?>">

<?php the_title();?></a>
</ul>

<?php endwhile;}}}?>