White-light LEDs never cease to amaze me. My dentist wears one on a headband for close work. The thing appears to have nearly the luminosity of an arc lamp, yet its housing is just barely warm at full brightness.
As someone who grew up using various types of high-intensity miniature lamps in different projects, high-intensity white LEDs are science fiction come to life.
Of course, the iPad or iPhone is certainly SF-come-to-life too, but the white LEDs are more "energy-ish" as opposed to "compute-power-ish."
I'll tell you this... if they can improve battery technology as much as they've improved the luminosity of LEDs in the last forty years, it'll be pretty amazing.
The key to the white LED was the Blue Laser. When I was in college, my TA was the one who developed the first blue laser in North America and was interviewed on CNN. Of course, it helped that Amber was very good looking.
http://androidcommunity.com/student-wins-science-fair-with-30-second-phone-battery-charger-20130520/ ~ also on a Freerepublic thread. And, http://green.autoblog.com/2013/04/22/university-illinois-recharges-li-ion-battery-thousand-times-faster/ covered in Freerepublic as well. I don’t begin to understand how these little beggers work and all the explanations by the folks who developed them sound like gobbledygook ~ but in the windmill racket they were using simple iron hydride batteries that could hold fantastic amounts of current for 5.5 hours ~ and as that business ‘wound down’ those batteries went on the market cheap ~ they’re huge. Worth reading about they handle immense loads ~ like a very large version of these very small devices. Makes you wonder what other physics they’re tapping into