Very cool but definitely NOT open source and thus, from what I can tell, not applicable for being used in your own app w/o licensing or something he rolls out in the future. Still great work.
Yeah this is definitely really cool, and great UI imo. Could be used to bring the TI-83 to the browser. Lord knows we need an intuitive interface to bring both simple and complex mathematical operations (from pre-algebra to...calculus, linear algebra, diff eq, and some statistics) to the browser. With no Flash! This could definitely be a step in the right direction.