The day where you can say goodbye to lame laptop batteries draws near, as a preproduction unit of the UltraCell XX25 micro fuel cell system was demonstrated at the Intel Developer Forum. The power source s methanol fuel can keep a laptop going for two days. These fuel cells are hot-swappable, too, so they could keep a laptop running indefinitely, as long as you have fuel. Imagine that, battery life measured in days or weeks rather than hours.
The main objection to fuel cells and laptops is that sticky problem of taking such explosive fuels such as methanol or hydrogen onboard aircraft, but these preproduction units might be able to sooth such fears. They were developed for military use in combat situations, and are hardened to survive lots of jostling around and operate in harsh environments from well below zero to oven-like desert conditions.
UltraCell says we might be seeing a commercial version by the end of this year.