Just spotted this press release about a new solar-powered sensor module by EnOcean.
Now there is a company that gets it. As the Long Emergency plays out, implementations like these will take off.
Along this train of micro-power thought, why don't children's toys have solar chargers built in? They would certainly charge a lot faster outside than in, perhaps persuading more kids to go outside. Once such a toy reached the end of its' play-life the charger module could be reused elsewhere.
For the more mature (ab)user of power, more companies are coming out with alternatives to yet another brick on the wall.