[T-Mobile Samsung Galaxy S II SGH-T989] elesbb:
Good info, but not all is true. I shall clarify :) FYI not putting anyone down, just trying to educate the general public :D

This one is not true. Ondemand is a high performance governor. Its pretty straight forward, In english, calculations are as follows "Oh crap, i have a lot of work to do, lets jump up to max CPU" ....... work is done ... "okay now we can calm down again lets slow down." now that "work" that needs to be done, could be simply tapping the screen. If you look in the advanced settings, you can ignore nice load. So that helps to save battery. Try it, open SetCPU or any live CPU monitoring app, simply touch the screen and watch the clock speed jump to max! :) The best battery and performance combo, would totally be smartassV2. It cycles through the CPU rates before reaching max, and it generally stays at an "ideal frequency" which can be set using init.d or set by dev. If you set it to smartassV2 and try above test, you will notice that it stays at whatever the ideal frequency is. In english, the smartassV2 governor says "Okay i have a little work to do, CPU is at 100 percent use, lets bump up the frequency *how much depends on again init.d settings or dev defaults* oh wait im still in a deep pile of work, bump up again!" Now it does that at lightning speeds of course. But simply using CPUSpy you can tell that there are more times spent in EACH frequency, not just max and min and a couple seconds of time spent in between. Conservative is a lot like smartassV2, however, its very much more laggy and tries to stay down at the lower end of the CPU clocks regardless.

This is true across the board for any LCD display. LCD works off of RGB(Red green blue) colors, when they ALL are on at full power, you get the color white. When they ALL are off, you get black. So comon sense says, turn them off and you arent draining power, Thats one thing i miss in CM9, RenderEffects.

Um yes it does, it stays at the lower end of the speeds for which are set as max/min.

Not only that, if you, like me, work in a factory or a building with thick walls, jumping in and out of service will also greatly reduce battery life. When yoou have NO service, the phone never sleeps, it just keeps searching and searching and .... I put mine in airplane mode whenever i know im not going to be using it.

oh how true and unfair >.<

PS: about the governors, i referenced the source code.

PSPS: Battery life is not soley determinant of CPU clock speeds undervolt settings and kernels. 99 percent of your battery life is determined by use. 98 percent is determined by location. With the same phone running two different everythings.(ROM Kernel radio) being operated exactly the same(same amount of time spent with screen on, data transmitions etc) they will have totally different power consumptions based off of location. I get crappy service at my dads house. Deep sleep yields a drain of about 5-14mA up at my moms house, i get full reception. Deep sleep yields a drain of 2-4mA...

The main thing to look for if you are experiencing horrendous battery life, are things called "wake locks" they simply take the device out of deep sleep. (i.e. notifications)

Hope i added to the general knowledge :)