Index: trunk/wp-includes/formatting.php
===================================================================
--- trunk/wp-includes/formatting.php	(revision 11705)
+++ trunk/wp-includes/formatting.php	(working copy)
@@ -1696,7 +1696,7 @@
 
 		$text = apply_filters('the_content', $text);
 		$text = str_replace(']]>', ']]>', $text);
-		$text = strip_tags($text);
+		$text = trim(preg_replace('|\s+|',' ',strip_tags($text)));
 		$excerpt_length = apply_filters('excerpt_length', 55);
 		$words = explode(' ', $text, $excerpt_length + 1);
 		if (count($words) > $excerpt_length) {