<?php
                        $categories = get_the_category($post->ID);
                        if ($categories) {
                             $category_ids = array();
                             foreach($categories as $individual_category) $category_ids[] = $individual_category->term_id;

                             $args=array(
                                 'category__in' => $category_ids,
                                 'post__not_in' => array($post->ID),
                                 'showposts'=>4, // количество ссылок
                                 'caller_get_posts'=>1,
                             );

                        $my_query = new wp_query($args);
                             if( $my_query->have_posts() ) {
                                 echo '<ul id="related">';
                                 while ($my_query->have_posts()) {
                                     $my_query->the_post();
                                 ?>
                                     <li><a href="<?php the_permalink() ?>" title="<?php the_title('', ''); ?>"><?php the_post_thumbnail('thumbnail', array('alt'=>'', 'title' => get_the_title()))?></a>
                                     <a class="link" href="<?php the_permalink() ?>"><?php the_title(); ?></a></li>
                                 <?php
                                 }

                                 echo '</ul>';
                             }
                             else {echo "Похожих обзоров нет.";}
                             wp_reset_query();
                        }
                        ?>