I've always wonder what the huge lag in commercial batteries stems from? Back when I worked for a hobby distributor, LiPo (Lithium Polymer) was becoming "all that, and a bag of chips." On a one or two cell pack you could run your car or plane with more torque (read: amps) and longer run times, like on the order of double and triple, all with a lighter package. The problem (maybe what delayed it coming to powertools) was the propensity to spontaneously burst into flames if charged incorrectly.
But really, I still see "great strides" in battery-powered alternative energy things using NiMh or Lead-Acid. I would think since LiPo has entered the tool market (at least a couple of manufacturers), the charging issues must have been addressed (there is no lazier charger than a power tool charger).
***Ok, I just found my own correction: Lithium
Ion recently made it to power tools and consumer electronics. Lithium
Polymer has yet to make an appearance, cost being the holdback, I guess. Though acording to Wikipedia (the know-all and trust-some source) Hyundai is working with LiPo for their electric car.
Ultimately, I'm gonna keep watching the Hobby industry to be ready for the "next" thing...they're innovators!