<?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,
		'caller_get_posts'=>1
		);
	$my_query = new WP_Query($args);
	if( $my_query->have_posts() ) {
	while ($my_query->have_posts()) : $my_query->the_post();
	WHERES THIS PART?
	endwhile;
	}
	else {
	echo 'No Related Posts';
	}
}
?>