Check if post has more than one image attached in WordPress

check-post-image.php

<?php
/**
 * Check if post has more than one image attached
 * 
 * @author Chris Robinson
 * @link http://contempographicdesign.com
 */
$attachments = get_children(
    array(
	'post_type' => 'attachment',
	'post_mime_type' => 'image',
	'post_parent' => $post->ID
    ));
if(count($attachments) > 1) { ?>
    <!-- Do something like show a slider -->
<?php } else { ?>
    <!-- Display a single image -->
<?php } ?>