. . . but – for the time being -- only if you are flying with Japan Airlines JAL and in either executive or first class.
The Japanese airline company has announced that throughout August it will provide their executives and first class travelers with a Nintendo DS Lite (yes, yes the really nice looking one) and several top titles to choose from during the flight. The handheld consoles have been altered to turn off their wireless capabilities, and their use won’t be allowed during take off and landing.

You can check JAL site for Nintendo DS equipped flights.

Via Yahoo! Games