I just upgraded my iPhone 3GS from 4.0 to 4.1 using the latest version of PwnageTool a few days ago. But I'm noticing that my battery drains its power much more quickly than 4.0. I can't even last more than 3-4 hrs. before it's completely dead. When I had 4.0, the battery use to last me a whole day! Is there anything I can do to improve battery life? I've turned down my brightness all the way and have even turned off wi-fi when I'm not using it. Can I revert back to 4.0? Please help!