I am curious to see if anyone else is experiencing this issue with their 3GS. My iphone was showing approximately 70% charge this afternoon when it suddenly went to the "spinning circle" loading screen before shutting itself down. After plugging the phone into a power source, it still would not turn on, but instead showed very low battery life. The phone would then turn back on after plugging and unplugging the device, but did so sporadically. This happened a couple more times throughout the night. After a couple hard reset attempts, I moved forward with a restore through iTunes. The iphone appears to be working now, but I'm going to be keeping an eye on the battery life. Update: It appears the battery is draining rather quickly since the restore. I might have to make an appointment with the Genius Bar.