Tip: iPhone4s Battery drain bug
It seems that iOS 5′s GM release introduced a bug that causes the Setting Time Zone function to keep the location tracking circuitry running constantly, draining battery power considerably. Switching it off may mean that your iPhone will no longer set its own time zone when you travel, but that’s a small price to pay for having your iPhone last more than 12 hours on a full charge. We have tested this method on 4 different iPhone 4s. All have reported drastically improved battery life after switching ‘Setting Time Zone’ off. This feature can be accessed from the Settings app, in the “System Services” section of “Location Services.” The website suggests that switching the “Setting Time Zone” toggle to off will result in improved battery life.
It’s likely that Apple will release a minor update that will improve the handset’s battery life.