hilarious stuff!
you should also consider logging your last 3 hours of reading and post it online, like how your targeted audience for this post of yours just recently did! :D
If you read the docs, he's not programming the microcontroller in JavaScript - just running a native shim on the microcontroller and then communicating via serial. So it's basically a node.js library to use an Arduino as a dumb I/O card for your PC, not to program the Arduino in JS.
and all the built in stuff is just plain C++ too and can be found in the lib directory.
I really like how easy it is to hack prototypes together with Arduino. I recently moved my own prototypes from PIC24 to a Teensy++ (a tiny little Arduino compatible board) and its made life so easy! Its a lot of fun to play with and the wealth of libraries makes prototyping a breeze. Just today I was tinkering with ultrasonic sensors and with bluetooth modules.
For end products, I'd use C and LUFA for atmels rather than Arduino (or a PIC24 if I want 16bit or some of the other fancy PIC24 features, like 40MHz Fcy on PIC24H! since I have no experience with non-8bit Atmel micros)
Arduino was built for the arts community who were already using Processing, allowing them to take what they already knew, and apply it to hardware. That's why it looks like Processing.
Of course, the Arduino board isn't limited to the Arduino programming environment. Hackers tend more towards programming the AVR directly, providing greater performance and environments more familiar to them.
I have been learning rails and had a similar project idea of developing a blog creator using this framework, but you have bet me to it! Now, I have to look for another idea. :)