Lot of users especially since iOS 4.3 reported an unprecedently fast battery drain. Many solutions were offered on the Internet, but none of them worked.
Recently I have found a Forum where the following was posted:
Number of users have been testing for many months the iPhone after iOS 4.3. The conclusion they made: the fast battery drain is caused by a simple phenomenon: AppStore App.
The workaround: Sign out of AppStore App (Settings > Store > Sign Out).
In the background of the problem lies the push notification related activity of the phone, namely of the AppStore App as the phone permanently tries to communicate with the Apple server.
To check this kind of activity you can use a simple app Netstat (it is free). Close all apps (multitasking bar), turn off wi-fi, location services, open Nestat.
The above mentioned method works. My iPhone's battery was draining in an unbelievable fast speed. After singing out of AppStore App the battery is at 84% with average use after more than 2 days .
To be on the safe side you can sign out of your Game Center account as well.