Power Management

Do any developers have input from their own experiences with working on source code for power management, or what roadblocks may lie ahead?

I'm particularly looking into code, kernel, subsystem, etc. I'm new to FreeBSD, but for my own curiosity, I'm currently reading up on power management in Linux and wondering how it compares to what could be done or is already done in FreeBSD.

I've had trouble in the past with battery life, even with the acpi-overview and the wiki entry for TuningPowerConsumption. Revisiting it now, I'd like to take a deeper look at how its done on the lower levels.

For the others who may be curious, here's a few Linux based articles on their power management:

Any input, mentioning of possible roadblocks, etc. would be greatly appreciated.