Index: wp-includes/general-template.php
===================================================================
--- wp-includes/general-template.php	(revision 5939)
+++ wp-includes/general-template.php	(working copy)
@@ -194,7 +194,7 @@
 	if ( !empty($tag) ) {
 		$tag = get_term($tag, 'post_tag');
 		if ( ! empty($tag->name) )
-			$title = apply_filters('single_tag_title', $tag->slug);
+			$title = apply_filters('single_tag_title', $tag->name);
 	}
 
 	// If there's an author