So I was in the toy store the other day. Did you know remote control cars are still being sold with Ni-Cd batteries? Those have been outdated for years! They don't hold a charge very well, they can't be recharged unless they're completely drained, and they die after a couple years of use.
More expensive electronics have been using Lithium batteries for a while. These last longer, can be charged whenever, and hold their charge for a long time. But they can't be produced in high-powered versions. This is why we only see them in cell phones, cameras, iPods, and the like.
This, however, is amazingly sweet. Batteries and their lack of oomph is what's holding back portable electronics. Imagine something like this in a cell phone instead of a drill. Your battery lasts twice as long and reaches a full charge in under 10 minutes? I'll take two!