I had not heard of this low-cost, low-tech solution to a problem affecting the roughly 1.5 billion people in the world living without electricity until Sandy showed me her upcoming presentation for the class she's taking on innovation. (This video is part of that presentation.)
For more on this idea (and its application in Africa), see this report from VOA News.
(And, yes, some homes where these lights have been installed do have electricity, but it's not free, unlike these light bulbs.)