Gasoline prices have skyrocketed for the past few years, and the petroleum-related inflation is especially noticeable in recent months.
A new experimental concept has surfaced recently: instead of pouring gasoline into your hybrid car, and charge the battery during vehicle movement (e.g. braking), why don't we just charge the battery at home. This would further reduce the gasoline consumption for your hybrid vehicle.
It appears Google is also participating in this concept via their RechargeIT.org project: