Solar Flower Petal Street Lamps Bloom by Day, Illuminate the Night  

Inhabitat has a post on an elegant and efficient design for streetlights - Solar Flower Petal Street Lamps Bloom by Day, Illuminate the Night.

Designed for the Phillips Simplicity Event in 2008, the Sustainable City Light is an intelligent outdoor lighting system meant to enhance city life by providing accurate lighting on demand as needed. The LED lights feature motion sensors that are triggered once the sun sets by individuals walking in close proximity to the light. If no one is around, the lights conserve energy by remaining off.

Powered by the sun, the street light blooms open during the day to collect energy through its solar panels. The five solar panel petals generate more than enough power to keep the lights on and any extra power is fed directly into the grid for use elsewhere.