--- wp-includes/formatting.php.r11518	Wed Jun 10 20:29:59 2009
+++ wp-includes/formatting.php	Wed Jun 10 20:49:47 2009
@@ -702,6 +702,10 @@
 	$title = preg_replace('/\s+/', '-', $title);
 	$title = preg_replace('|-+|', '-', $title);
 	$title = trim($title, '-');
+	// Use uppercase hex digits in URI-escaped characters
+	$title = preg_replace_callback( '/%[a-f0-9][a-f0-9]/',
+									create_function( '$m', 'return strtoupper( $m[0] );' ),
+									$title );
 
 	return $title;
 }