How is that going to work? A 17" laptop, particularly a MacBook Pro, a higher-powered laptop than the MBA, will suck a lot more power than the MBA. Besides the fact that the battery will eventually degrade over time, end users like to carry spares around with them. Enter the theory: Silver / Zinc batteries.
ZPower has been working on silver/zinc batteries for some time. They promise 20 - 40% longer battery life per change than lithium-ion batteries. All this, without the explosiveness of Li-ion batteries.
Image courtesy: ZPower
And here's the kicker: their FAQ says:
When will ZPower batteries be available?
"ZPower batteries will be available in a leading notebook computer in early 2009."
Is Apple the leading notebook computer they're aiming for? It makes sense, but it's all a theory. Macworld is coming in a couple of days, though.