NASA researchers have reached an important milestone in developing a portable energy source that may someday give that hot pink, shades-wearing, drum-beating bunny a run for its money. A team of fuel cell experts at NASA’s Jet Propulsion Laboratory, Pasadena, Calif., has taken what have been traditionally large, bulky stacks of layered fuel cells and altered their design dramatically. They have designed a compact, flat fuel cell, reducing its weight substantially. The result is a portable fuel cell technology that may someday operate small, portable electronic devices, such as cell phones, laptops, handheld organizers and camcorders, for hours and even days at a time without recharging or using expensive, heavy batteries.