** Possible Fix ** It worked for me.
Ok guys, here goes . . .
The problem:
After having minor battery drainage, I decided to install the IOS 5.01 update. Boy did I regret it. After installing it, my battery when crazy. The phone completely drained from a full charge in about 4 hours with only slight use. By slight I mean a few texts, one or two short calls, and maybe 5 minutes total of web use. The phone was mostly in standby mode in my pocket.
I was pretty mad when this happened, so I went searching the web for answers.
These are the steps I took:
Warning: Proceed at your own risk. I take no responsibility for loss of data.
!! BACKUP YOUR DATA !!
Go to Settings > Location Services > System Services
Turn OFF the Following
Diagnostics & Usages
Location-Based iAds
Traffic
Go to Settings > Mail, Contacts, Calendars
Delete Any Mail Accounts You Have Listed (see Red highlighted note above for disclaimer)
Go to Settings > General > Reset > Reset Network Settings
Follow the Prompts (see Red highlighted note above for disclaimer)
The phone may restart. It could take a few minutes for the network to reset.
Fully Discharge the Battery Until the Phone Shuts Off
Try To Turn The Phone Back On
A Low Battery/Plug icon should display and the phone should not turn on. If it turns on, continue discharging until the Low Battery/Plug icon appears.
Fully Charge the iPhone (I was able to use the phone while on charge)
My results:
I unplugged the fully charged iPhone right before bed. When I woke up 8 hours later, the phone showed the battery at 100%(battery percentage was turned on). So far I am at 11 hours of standby time and 2 hours of heavy use (a lot of camera and video use along with wi-fi and app downloads) and my phone is only down to 72%. At this rate it will at least last all day.
I wish you luck with your battery woes!