This pegged my duo core at 100% for both cores. Realtime shadows are great and all, but if I needed to achieve them I'd imagine I'd use WebGL if I didn't care about CPU or battery.
Using jQuery for this type of problem seems a little out of place to me. That said, this is certainly "neat." THAT said, I don't believe this has real world practical value. Its too computationally expensive considering what it adds.
for a real world application – at okfocus we used our version of this effect on http://tugofstore.com and it added to the realtime "tug" effect by making it more of a visceral experience for users. perhaps ours is less computationally expensive idk.
Flash wasn't ridiculed because of how it looked. The principle of integrating interactive content into web pages is a fine one, so long as it's done in a way that's semantically consistent, machine readable, searchable, accessible, reliable, not too obtrusive, forgiving of network latency and performance, cross-platform, cross-device, and tolerant of errors -- the web, in other words. Flash was... not.
That doesn't mean we stop trying to make web pages look prettier.
Just to confirm, it's working well on Chrome 20 on Mac for me (no lag, not maxing out the CPU, very smooth). It's interesting from a technical perspective, although design-wise I can't really see any practical reason to use it. Fun though.
It may just be for demo purposes, but using the mouse cursor as a light source seems like the 2012 equivalent of animated GIF backgrounds. Might be cool it could you specify a point light source at a given coordinate and let the page render from there.