Pardon the cliche, but it's one of the holiest of Holy Grails of technology: Wireless power. And while early lab experiments have been able to "beam" electricity a few feet to power a light bulb, the day when our laptops and cell phones can charge without having to plug them in to a wall socket still seems decades in the future.

Nokia, however, has taken another baby step in that direction with the invention of a cell phone that recharges itself using a unique system: It harvests ambient radio waves from the air, and turns that energy into usable power. Enough, at least, to keep a cell phone from running out of juice.

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