This would be awesome if could model brightness around heat decay. Think about it, each keyboard press adds would add a small amount of "heat" making the keys brighter and brighter as you used them and eventually topping out at a certain point. Then when you stop typing have it dim according to a heat decay function... Might have to try this myself.
This looks really awesome. Does Mac OS provide (unofficial?) libraries for interacting with these lights? I wonder how hard it is to get something like this working on other laptops.