[ankushnarula]

Agree with the most of youir premise - but a magnetically aligned and secured pogo-pin interface on the bottom back edge of every MacBook might be superior to inductive charging, which wastes electricity and generates too much heat. Such battery packs could also include a second pair of pass-thru pins for stacking and connecting to a direct wall power adapter.

[warrenm]

was not really thinking about MacBook, more iPhone (and, possibly iPad) ... but that is an intriguing idea, too: supply a basic battery that would last for X long, and have a pass-through (hermetically-sealed, if you wanted to move into the IPS zone for dust/liquid resistance) MagSafe (or similar) connector for additional battery packs on the bottom

I could totally see getting a second laptop-footprint-shaped pod for my MBA that would click on and give me another 20-40h of run time between charges!