Power Mode Manager
One thing Windows has yet Linux lacks is proper support for battery use. There should be support for different power modes that change depending on the power status. Details are up for debate.
The idea of "provide power profiles" keeps coming up, but it's not something that gnome/linux will do, and I'm not convinced of it either. We should always save as much power as possible, not just when we are on battery. We already don't index the file system by default (like tracker, which certainly eats a lot of IO and power), and compiz animations don't really take that much power; the biggest problems these days are wakeups from wifi and touchpad interrupts, and firefox is also having a fair share of wakeups (check with powertop). These are the problems we need to address first. Changing the entire desktop behaviour or features based on the power status would be unexpected and is also not something we want to encourage.
-As far as CPU frequency scaling goes, a gnome-power-manager dev has articulated why it is not wise to dabble with these kinds of options nowadays: