Index: formatting.php
===================================================================
--- formatting.php	(revision 12903)
+++ formatting.php	(working copy)
@@ -1812,7 +1812,9 @@
 
 		$text = apply_filters('the_content', $text);
 		$text = str_replace(']]>', ']]>', $text);
-		$text = strip_tags($text);
+		$excerpt_tags = apply_filters('excerpt_tags', '');
+		$text = strip_tags($text, $excerpt_tags);
+		$text = force_balance_tags($text);
 		$excerpt_length = apply_filters('excerpt_length', 55);
 		$excerpt_more = apply_filters('excerpt_more', ' ' . '[...]');
 		$words = explode(' ', $text, $excerpt_length + 1);