The cross-sectional area of the wires and contacts of a standard USB cable are designed for a maximum of about 1000 milliamps of current. The color display of the NC uses more power than the e-ink display of grayscale Nooks, so a full charge with a standard USB cable takes many hours with the display off. The most common solution to the power limitation of USB is to put two USB connectors on the device and connect it to a computer with two USB cables; I have several disk drives like that. To avoid needing two cables, B&N instead chose to use a special non-standard USB cable which has extra contacts. Chargers and cables not specifically designed for NC will work, they will just take longer.
Remember: the big print giveth, the small print taketh away.
