The changes we put into Precise 12.04 LTS pm-utils /usr/lib/pm-utils/power.d address a lot of the best low-risk power savings for a broad range of machines based on some in-depth analysis with a high precision multimeter. These scripts cover power savings using hdparm, Intel Audio powersavings, PCI device power savings, PCI-e ASPM, USB bluetooth, SATA ALPM, Wireless, scheduler tweaks and VM dirty page settings.

I suspect these changes in 12.04 are a little more comprehensive than the laptop-mode-utils.

For a write up of the testing used for the 12.04 pm-util chanages please refer to:

We also did a lot of analysis of the PowerTop power saving recommendations that proved to work well (and reliably) across a range of machines and incorporated these into the pm-utils power.d scripts (see http://kernel.ubuntu.com/~cking/power-benchmarking/powertop-good-bad-recommendations) and we ran some community based crowd-sourcing to test these changes, see:

I hope that throws some light into the kinds of savings one can achieve with the updated pm-utils scripts.

For more details about ways to save power, please also consult: