According to The Hollywood Reporter, Japanese airplanes no longer allow gaming systems with wireless functions to be played on board. The revised law went into effect Monday and passengers are asked to not play systems like the Nintendo DS. Apparently Japan's transport ministry concluded the "electromagnetic waves emitted by the consoles have the ability to interfere with aircraft navigation systems and other devices."
Passengers are still allowed to use game systems that don't have wireless communications functions, so hopefully you didn't throw out that GBA yet. Wireless computer mouses and headphones not provided by the airlines are also banned now. No word yet if American planes will implement similar rules, but if they do they'd better drop the cost of liquor 'cause we'll be damned if we're actually going to start reading on flights.