Index: wp-includes/formatting.php
===================================================================
--- wp-includes/formatting.php	(revision 18126)
+++ wp-includes/formatting.php	(working copy)
@@ -2135,7 +2135,7 @@
 		'♦' => '♦'
 	);
 
-	return str_replace( array_keys($to_ncr), array_values($to_ncr), $text );
+	return apply_filters( 'ent2ncr', str_replace( array_keys($to_ncr), array_values($to_ncr), $text ), $text );
 }
 
 /**