I have ordered these
http://www.reelight.com/
The only drawback is that they are designed to go on axles with a nut, not a quick-release skewer. I believe they can be safely mounted on the nut side of a quick-release, but that puts them on the non-traffic side in the USA. Because they use LEDs their light pattern is very narrow and this isn't very helpful. However, my husband's bike (a Giant Revive) has nutted axles and has received these on the traffic side where the work well.
I expect these types of lights will become more widely available, and hope to see the Pedalites required on children's bikes soon.