I'm working with the developer of Blockly. Note that at this point it's more of a library for creating browser-based Scratch (or App Inventor) style Visual Programming Language environments than it is a complete application. The demos are there to give a good idea for how to use and integrate the library into your own web apps. As such, it might be a good starting point for someone who wants to build out a more complete app to give some kids a head start to writing code.
If any of you want to try and do something interesting with Blockly, feel free to let me know. I might be able to get you connected to the developer.
-Mark