Actually it's more like 50:50 between improved energy density in batteries and "other stuff" - most importantly "better" CPUs and smarter power management in ot

Actually it's more like 50:50 between improved energy density in batteries and "other stuff" - most importantly "better" CPUs and smarter power management in other hard/software. The battery in the laptop used to write this comment could power most "ultrabooks" (or it's direct successors) for >24 hours (that is, from the claimed battery life of the newer devices)