Index: wp-includes/feed-rss2.php
===================================================================
--- wp-includes/feed-rss2.php	(revision 5083)
+++ wp-includes/feed-rss2.php	(working copy)
@@ -10,6 +10,7 @@
 	xmlns:content="http://purl.org/rss/1.0/modules/content/"
 	xmlns:wfw="http://wellformedweb.org/CommentAPI/"
 	xmlns:dc="http://purl.org/dc/elements/1.1/"
+	xmlns:slash="http://purl.org/rss/1.0/modules/slash/"
 	<?php do_action('rss2_ns'); ?>
 >
 
@@ -41,6 +42,7 @@
 		<content:encoded><![CDATA[<?php the_excerpt_rss() ?>]]></content:encoded>
 	<?php endif; ?>
 <?php endif; ?>
+		<slash:comments><?php echo get_comments_number(); ?></slash:comments>
 		<wfw:commentRss><?php echo comments_rss(); ?></wfw:commentRss>
 <?php rss_enclosure(); ?>
 	<?php do_action('rss2_item'); ?>