Justin Parks

<div class="thumbnail">
	<?php if ( has_post_thumbnail() ) { // the current post has a thumbnail
	} else echo '<img src="/wp-content/themes/yourtheme/images/default-thumb.jpg" />'; { // the current post lacks a thumbnail
	} ?>

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