The Nintendo 3DS is the first dedicated portable video game system to come with a charging station. Nintendo calls it a cradle.
With its inclusion, Nintendo is nudging 3DS owners to dock their system all the time, probably to keep them from being without a charge, given that the 3DS battery could pack as little as three hours of power on some settings.
The cradle is easy to use. I got my 3DS today - it goes on sale in North America on March 27 - and will see if this thing is a convenience or an encumbrance. Hopefully the former.