Finally, OLPC has realized that ARM uses less power than x86… They are producing XO-1.75 that can be recharged with a couple of hours on the crank. Still, their price is about $165, too high for many of its target-users. I expect by next year they could be within the original $100 range. The next model, XO-3 should run for 1 watt.
It is interesting to speculate on the ultimate limits to the price of such technology. Pocket calculators got down to less than $10 but OLPC and tablets have huge displays which may be the limiting factor. Perhaps $100 is the limit and that may be hard to reach if the price of oil keeps rising. Perhaps we will see more wooden PCs soon.