I, like many, updated my iPhone to 3.1 when it became available. The upgrade went smooth to start and I was enjoying the new features. Until yesterday everything was going great anyway. I went to go watch TV for a few came back to my phone and it was pretty warm to the touch as if I had just finished playing a game. Odd though since I haven't used it for over an hour. So, I restarted the phone, hard reset the second time. No differences. This afternoon I restored (using a backup since I didn't want to destroy all my information if I didn't have to). No change. One thing I noticed though was that my Usage panel had the same time for both Usage and Standby. Which is odd as usually I get 15-20 hours of Standby per charge and about 6 hours or so of actual Usage. Locked the phone. Let it sit for a few minutes, came back and both times had increased the same amount. So clearly something is happening in the background even when the phone is locked. (I should note I am not jailbroken and no hacks are applied, this is a bone stock 3GS with Apps installed) First thing I did was shut off Wifi, no change. Then Location Services, no change. Then 3G, no change. Turned off Push for email, no change. Turned off Notifications, no change. Turned airplane mode on. Woot, we have liftoff. Standby went up, Usage stayed the same just as it should be when the phone is locked with no apps running. So I turned everything back on as it was before hand. Then went into email and made each of my email accounts inactive, one at a time. Turns out my Exchange account was causing the problem. When I made that one inactive it leveled out exactly how it should have. Anyone else who is having severe battery issues able to confirm/deny whether they have an Exchange account setup and whether making it inactive solves your problem? Or any other emails for that matter. I suggest trying to narrow it down the same way I did if you have the time to test it out. Post results below please.