Its larger form factor and bigger battery mean the iPhone 5 should last longer on a single charge. But to overcome the fact that battery technology still basically sucks, Apple has applied for a 'shake to charge' patent that uses electromagnetic induction to convert everyday motions into extra battery life.
In Apple's system, a small lubricated magnet would move across a series of printed coils inside an iPhone or iPod, inducing a small current which could be used to generate power and charge the battery. What sets Apple's design apart from the various radios and flashlights that already use this approach is the flat coils which can be easily printed using modern circuit production techniques.
Just don't expect this to be the flagship feature on the iPhone 5S. Smartphones use far more power than this induction system could ever replenish, even with continuous vigorous shaking. But as their components get more energy efficient, somewhere way down the line this could be a plausible alternative to plugging in your phone every night.