title: Add extra class to last item in WP loop
body: <p>I'm using this to pull out the four most popular posts based on comments:</p>
  
  <pre><code>        &lt;?php
              $pc = new WP_Query('orderby=comment_count&amp;posts_per_page=4'); ?&gt;
              &lt;?php while ($pc-&gt;have_posts()) : $pc-&gt;the_post(); ?&gt;
              &lt;div class="popular-post-item"&gt;
              &lt;span class="popular-title"&gt;&lt;a href="&lt;?php the_permalink(); ?&gt;" title="&lt;?php the_title(); ?&gt;" class="post-links"&gt;&lt;?php the_title(); ?&gt;&lt;/a&gt;&lt;/span&gt;
              &lt;span class="popular-author"&gt;by: &lt;?php the_author() ?&gt;&lt;/span&gt; 
              &lt;a href="&lt;?php the_permalink(); ?&gt;" class="action"&gt;Read Full Article&lt;/a&gt;
              &lt;/div&gt;
          &lt;?php endwhile; ?&gt; 
  </code></pre>
  
  <p>What I need is the fourth: </p>
  
  <pre><code>        &lt;div class="popular-post-item"&gt; 
  </code></pre>
  
  <p>to have another class added called .last</p>
  
  <p>any ideas?</p>