I've installed Ubuntu 12.10 a few days ago and I have only been able to get up to one hour of battery life. When running Windows 7 I get up to 3-4 hours.
My screen is ultra bright, even though the screen brightness is set to the minimum (I installed xcalib to dim my screen, but it doesn't improve the battery life)
I read about Jupiter and installed it, but it doesn't have a noticeable effect.