On the topic of Hypercard, there seem to be a few other interesting authoring tool projects around. I’ve listed a few below: anyone got any more I should look at?
Squeak has some pretty big names behind it.
PythonCard seems a way away from prime time, but sounds like an interesting project, with a good motto: “Simple things should be simple and complex things should be possible.”
The Skate project aims to recreate SK8, which was sort of like Hypercard on steroids, written in MCL.