my i3g don have this battery problem except i m using tethering with my laptop. I also have use Push mail , but off notification. Just now morning i listen to song , around 1 hours, decrease 8% of battery.

U need to jailbreak and install SBSettings, then u go to "Process" and can see all the process running.
I personally think jailbreak have more or less effect battery life, if u play hard on your phone theme, but not a critical point of battery drain fast la.

@zdongdongz,
ur case are damm serious...tap tap revenge wont cause the battery drain , I installed before and many users played since last year, so far no complaint. I duno this battery issues exist on every i3gs users , or only random users. We cant assume the quality of every units of i3gs is the same, some might get better, some might unlucky.

@Jasie
Here is my opinion, actually you wont too worry about the life of battery. iPhone3G and iPhone3GS have different hardware set. Apple do upgrade on component of 3gs to increase the phone performance and speed, but the battery is REMAIN the same like i3G. So, of course the hardware upgrade will absolutely use more energy to support that hardware, right? Then it will cause drain of battery.And also Apple would not expect users to use iPhone to play game all hours, or surf net few hours continously.
It cant compare with other nokia or SE as iphone have bigger screen and CPU is higher than those normal phone. It is just like you laptop battery can tahan you surf net all the day?
I can see this happen on i3gs than i3g more obvious and complaint by many users that they need charged battery everyday. I just can advise use i3gs wisely, always in sleep mode if doesn't use it.

Even someone had said FW3.1 will update about battery, but don't expect too much on it. It might nothing different after upgrade.

The battery of i3gs basically is same with i3g. However, due to upgrade hardware on i3gs, and it need more energy to support those new hardware spec, so it is normal battery drain faster than i3g. You can tahan until 2 days, actually not bad already.