[Galaxy S I9000 General] lpy:
Just to keep all my findings in one post, here is everything together...

These are only my experiences, so YMMV.

Tell me about this Wifi bug

UPDATE: I can now confirm that hardcore's K12C kernel fixes the Wifi battery drain bug that exists in (2.2.1) JPY and JPY-based ROMs. Well done buddy!

That there is a JPY 2.2.1 Wifi bug that DOES NOT exist in 2.2

A weak Wifi signal in 2.2 does not cause the phone to use more power and stay awake, but it does with 2.2.1!

2.2 JP5 (AU firmware): 4-6mA on standby, regardless of signal strength

2.2.1 JPU & JPY: 4-6mA on standby better than -70dBm, 25-250mA worse than -70dBm

If you mainly use Wifi with the charger connected and have the Wifi set to switch off when the screen goes off when on the battery, it shouldn't bother you.

Odin vs Kies

This was mentioned earlier in the thread the flashing with Kies may be better for the battery. I've flashed with both methods and have not experienced abnormal battery drain using Odin

Phone drops to 98% when I d/c the charger

It appears Samsung has altered the calculations in 2.2.1 which now works much the same as the Galaxy Tab. This appears to be only a visual thing and therefore should not affect battery life.

I surf the web for a little while and my battery has lost X% in only 30 minutes

And so it should. I did some general browsing whilst keeping an eye on the meter, and it generally hovered between 150-500mA, and that's with the brightness on minumum. On maximum brightness it was peaking around 900mA! In theory you'd be lucky to get 3 hours of browsing time using a standard 1500mAh battery.

The simple task of scrolling up and down is also a very big battery killer.

I suspect high CPU usage may be contributing to battery life

I use an app called Usage Timelines, which is very handy in montoring CPU usage and spotting when something isn't right.

Getting real bad battery drain, how do I know if my phone is properly sleeping? Is it an app, or the firmware to blame?

Many people are quick to point the finger at Samsung in regard to battery drain. Personally I think they've done an excellent job with 2.2, and would put any battery issues down to an app, or custom ROM, although I know some may disagree.

1mA on standby (see below) IMO is excellent.

2.2.1 also does a great job (Wifi bug aside).

After pressing the Home key to wake your phone, there should be a slight delay before the screen awakes (around one second). If the screen wakes instantly, your phone is not sleeping properly, thus causing battery drain.

Buggy apps can also prevent the phone from properly sleeping. An example is XiiaLive (I rarely use it now), which does (but not always) cause this to happen. After listening to a stream, my phone sometimes refuses to sleep (see above) after closing the program. I have to then reopen and close the app without doing anything else, and then my phone will sleep. This is just one example of how an app can cause battery drain.

So how much current exactly does stuff use?

2.2 JP5 AU & 2.2.1 JPY Firmware

Phone off: 0mA

Screen off, Idle: 1-3mA

Screen off, Idle, 3G on (full signal): 2-4mA

Screen off, Idle, Wifi on: 3-7mA

Screen off, Idle, Wifi on: 25-250mA (JPY firmware with weak Wifi signal)

2.2 JP5 AU Firmware

TWLauncher, default background, no icons, minimum brightness: 93mA

TWLauncher, Aurora animated bg, no icons, minimum brightness: 158mA

TWLauncher, default background, no icons, maximum brightness: 205mA

TWLauncher, Aurora animated bg, no icons, maximum brightness: 228mA

You can find some more tests I did a while ago on this page:

http://xdaforums.com/showthread.php?p=9672410#post9672410

It also seems that there is no difference between 256HZ and 500HZ.