WordPress shortcode Display the loop.php

/*
WordPress shortcode: Display the loop
From http://www.wprecipes.com/wordpress-shortcode-display-the-loop/
*/

<?php
function myLoop($atts, $content = null) {
	extract(shortcode_atts(array(
		"pagination" => 'true',
		"query" => '',
		"category" => '',
	), $atts));
	global $wp_query,$paged,$post;
	$temp = $wp_query;
	$wp_query= null;
	$wp_query = new WP_Query();
	if($pagination == 'true'){
		$query .= '&paged='.$paged;
	}
	if(!empty($category)){
		$query .= '&category_name='.$category;
	}
	if(!empty($query)){
		$query .= $query;
	}
	$wp_query->query($query);
	ob_start();
	?>
	<h2><?php echo $category; ?></h2>
	<ul class="loop">
	<?php while ($wp_query->have_posts()) : $wp_query->the_post(); ?>
		<li><a href="<?php the_permalink() ?>" rel="bookmark"><?php echo $thumbnail_image; the_title(); ?></a></li>
	<?php endwhile; ?>
	</ul>
	<?php if(pagination == 'true'){ ?>
	<div class="navigation">
	  <div class="alignleft"><?php previous_posts_link('« Previous') ?></div>
	  <div class="alignright"><?php next_posts_link('More »') ?></div>
	</div>
	<?php } ?>
	<?php $wp_query = null; $wp_query = $temp;
	$content = ob_get_contents();
	ob_end_clean();
	return $content;
}
add_shortcode("loop", "myLoop");