For all its usefulness, where are those wonderful hypercard stacks now? That's right you can't use them anymore or at least not that easily. This is due to the fact that it's a proprietary platform that the vendor stopped supporting.<p>Although google's appengine is more open, a lot of its key components are proprietary and can't be easily rebuilt. So while hypercard and appengine are both wonderful technologies, I believe people should prefer something more open. This allows you have an out in case google stops supporting appengine or does something that prevents you from using it effectively.