That right guys, prototype 1.6.0 is on it's way and there is one aspect I want to share with you. In stead of using the old-fashioned 'http-header' way to transport JSON, the prototype framework now eats files with the content-type 'application/json'. A short example:

1. First, we will use prototype to make an ajax request.

    new Ajax.Request('ajax.php',{ onSuccess: handleSuccess }, method: 'get' });

2. After this, on the serverside we set the json headers and output the formatted data using the Services_JSON class:

   <?php
   require_once "services_json.class.php";
    
   /* Set the JSON header */
   header("content-type:application/json");
    
   /* Format some data */
   $aData = array("Car", "Plane", "Train");
    
   $oJson = new Services_JSON(SERVICES_JSON_LOOSE_TYPE);
    
   /* Output */
   echo $oJson->encode($aData);
   ?>

3. And finally this alerts 'Car', 'Plain' and 'Train':

   function handleSuccess(transport) {
     $A(transport.responseJSON).each(function(str) {
       alert(str);
     });
   }