Apple has posted some information and tips about optimizing the battery life on your iPhone.
Paying attention to just a few commonsense pointers will pay off with a longer battery lifespan and battery life for your iPhone. The most important thing is to keep your iPhone out of the sun or a hot car (even the glove box). Heat will degrade your batterys performance the most.
Apple indicates that their engineers are finding new ways to optimize your battery, so make sure you have the latest software updates. Other common sense tips include
- Use Phone regularly. Go through at least one "charge cycle" per month.
- Lock/Sleep your phone when not in use
- Turn off Wifi to save power
- Turn off Bluetooth to save power
- Turning on Auto-Brightness
- Turn off the Equalizer (iPod setting) if you don't use it