[citation][nom]pei-chen[/nom]The technology behind this is so simple I can't believe Tom's people think this is hard to make.The LED will only come on when pressed. It will be powered by a small rechargeable battery that got recharged every time it is connected. The computer will also tell the flash how full it is every time something is transferred or taken out of it.[/citation]
More correctly;
I'd expect that regardless of how it is powered, the lights are based on a simple logic board hooked up to the NAND modules using some kind of encoder to tell it which blocks are used, which aren't, how they're grouped, then finally, and with simple hardware, turning it into a series of on/off's for the LEDs.
I could probably, given a little more knowledge of how flash memory is configured, create a simple, alas, inefficient, prototype myself.