I'm a Lego League coach. We're not allowed to use anything but the stock software and language for competition, but we can use whatever we want for the team project (this year's theme is Nature's Fury, and the kids are working on a way to easily use a car as a generator during a power outage). I'll have to look into this!
To communicate with the EV3 over bluetooth you don't need to make any modifications to the EV3 software at all so that could be a possibility although you'll need to check the rule book I suspect.
Right, what I mean is that they can only run programs (and communicate with the robot) in the Lego Mindstorms drag and drop language (which is actually decent). If we could have someone with an Xbox controller in the bleachers somewhere that would be cheating.
When I was in FTC a few years ago, "stock software" referred to both the software on the laptop and the software on the robot. In particular, I recall Linux on the laptop wasn't a supported OS for any of the allowed programming environments (LabView and RobotC).
Developments like this just make my day. The implementation is extremely small at the current stage but with exposure like this to a large audience it really opens a ton of doors. I'm all for getting younger people into programming and a nontrivial exercise such as this really allows someone to get a kid interested and have them run with it and get into some interesting territory. Javascript may not be the best language on the universe, but with the ability for application with things such as this for Mindstorms and Arduino really can open the doors for a whole new generation of hackers-to-be. Can't wait to toy with this stuff with my nephew when I travel home for Christmas.
We took a somewhat similar approach in college by building an autonomous Mindstorms robot using lejos. Here's one of the first test runs http://www.youtube.com/watch?v=DHZfAInCor8