Changing "public function handle(Zend_XmlRpc_Request $request = null)" to "public function handle($request = null)" is not critical, because type checking is also done by the following setRequest call. The other changes also don't seem to cause problems.

Patch follows:

 
Index: Zend/XmlRpc/Server.php
===================================================================
--- Zend/XmlRpc/Server.php      (revision 6103)
+++ Zend/XmlRpc/Server.php      (working copy)
@@ -112,7 +112,7 @@
  * @copyright  Copyright (c) 2005-2007 Zend Technologies USA Inc. (http://www.zend.com)
  * @license    http://www.zend.com/license/framework/1_0.txt Zend Framework License version 1.0
  */
-class Zend_XmlRpc_Server
+class Zend_XmlRpc_Server implements Zend_Server_Interface
 {
     /**
      * Character encoding
@@ -368,7 +368,7 @@
      * @param mixed $class
      * @return void
      */
-    public function setPersistence($class = null)
+    public function setPersistence($class)
     {
     }
 
@@ -447,7 +447,7 @@
      * @param int $code
      * @return Zend_XmlRpc_Server_Fault
      */
-    public function fault($fault, $code = 404)
+    public function fault($fault = null, $code = 404)
     {
         if (!$fault instanceof Exception) {
             $fault = (string) $fault;
@@ -544,7 +544,7 @@
      * @param Zend_XmlRpc_Request $request Optional
      * @return Zend_XmlRpc_Response|Zend_XmlRpc_Fault
      */
-    public function handle(Zend_XmlRpc_Request $request = null)
+    public function handle($request = null)
     {
         // Get request
         if ((null === $request) && (null === ($request = $this->getRequest()))) {
@@ -726,3 +726,4 @@
         return $responses;
     }
 }