I've had my iPhone 4 for about a week now. the battery was absolutely terrible the first few days. i would charge to 100%, close every app, also i would double click and close every app in the multitasker to make sure nothing was running in the backgroun and i would go to bed... 6 hours later all in standby it would be down to 60% battery. also, last saturday i went out around 6pm with a full charge and by 2 am the battery was literally down to it's last breath. i guess during the week i did not notice how absolutely terrible it was because i am either at home or at work and always close to a charger. so, before i went to the apple store, i did a little googling and concluded that most likely there were apps running in the background even though i would close all the apps including closing out the multitasking stuff. there must be an app that was corrupted, so i did a full reset and restored my phone as a new iphone, which ensured i brought over none of the old settings. i decided not to install any apps until testing the battery to see how it went monday night i went from 100% charge to 96% overnight, i then did not charge at all during the day and was at 34% around 8pm. and last night i went from 100% charge to a .... 100% charge in the morning!!! so let's see how long this battery last today, but it seems like the reset got rid of the corrupted apps and i got my battery back. i think the corrupted app was words with friends. as of last night, almost all my other apps were back on the phone and tonight's charge i will re-install words with friends and see if it still works. anyways, hopefully that helps out some of you who are having terrible battery life.