The article seems a bit quick to dismiss Ryobi's little 4V batteries; seems plausible to take 5 of those, build an enclosure for 'em, and get the sort of 20V battery proper power tools typically expect - then multiply that 5-piece unit for greater capacities. I'm sure it ain't
quite that simple, but it'd still be pretty neat.
On another note, if we ever get to the point where DeWalt makes a ruggedized laptop or tablet powered by their 20V battery packs, that'd also be pretty neat.