In my experience, most linux distro's battery management doesn't even match windows xp out of the box (no clear way to tune it). It is the only thing that is stopping me from transitioning to linux full time.
That's a good point. From personal experience, I strongly suspect this is mostly due to lack of power-management in the GPU drivers. In fact, on machines with Intel integrated GPUs I've seen battery life as good as on Windows.
Looking at the battery management on the 10.04 beta, the options seem very similar to the ones on my mac book. What do feel is missing ?
It's not the options, it's the actual power management. I have a netbook with XP and Lucid beta. The battery lasts 6 hours on XP and only 4:30 on Lucid. Both OSes are set to dim the screen and spin down the hard disk on battery power. The fan also comes on a lot more often when I'm running Lucid.
The opposite happens here, when I switch from Lucid to Vista. Did you try with a 10 year old version of linux? I think XP is 10 years old now.