Toshiba has demoed a methanol-based fuel cell prototype for MP3 players :
The first prototype, based on flash memory, sports a tiny fuel cell (size 23x78x10 mm) with 35-hours battery lifespan.
The second prototype, based on a microdrive, with a larger fuel cell (60x75x10 mm) is announced with 60 hours of music playback.
Those fuel cells are using almost pure methanol, so such a system is not risk-free, and if it becomes commercially available, it will for sure be forbidden in some places, such as airport or in planes; without forgetting that methanol is highly flammable;
One will have to wait till 2007 to find fuel cells in shops.
