private static function get_jetpack_user() {
    if ( !class_exists('Jetpack') )
      return false;

    if ( defined( 'JETPACK__VERSION' ) && version_compare( JETPACK__VERSION, '7.7', '<' )  ) {
      // For version of Jetpack prior to 7.7.
      Jetpack::load_xml_rpc_client();
    }

    $xml = new Jetpack_IXR_ClientMulticall( array( 'user_id' => get_current_user_id() ) );

    $xml->addCall( 'wpcom.getUserID' );
    $xml->addCall( 'akismet.getAPIKey' );
    $xml->query();

    Akismet::log( compact( 'xml' ) );

    if ( !$xml->isError() ) {
      $responses = $xml->getResponse();
      if ( count( $responses ) > 1 ) {
        // Due to a quirk in how Jetpack does multi-calls, the response order
        // can't be trusted to match the call order. It's a good thing our
        // return values can be mostly differentiated from each other.
        $first_response_value = array_shift( $responses[0] );
        $second_response_value = array_shift( $responses[1] );
        
        // If WPCOM ever reaches 100 billion users, this will fail. :-)
        if ( preg_match( '/^[a-f0-9]{12}$/i', $first_response_value ) ) {
          $api_key = $first_response_value;
          $user_id = (int) $second_response_value;
        }
        else {
          $api_key = $second_response_value;
          $user_id = (int) $first_response_value;
        }
        
        return compact( 'api_key', 'user_id' );
      }
    }
    return false;
  }