I heard this as well so when I got my android I didn't install one. But the battery life was horrible. Often, if I used the phone regularly during the day the battery would be dead by 9-10pm. I installed a task killer and killed everything when it booted up and killed a couple times a day. After that I suddenly have ~1.5 days worth of battery available. I'm not sure which app was being such a hog (I suspect it's an app that was refusing to let the phone go into sleep mode) but the task killer was most definitely necessary.

You're killing a mosquito with a howitzer, and you may have better battery life by letting Android do what it's supposed to, and find the offending application.

Download "Spare Parts", go into its battery history section, and select "partial wake usage".

You'll find out what (if any) app is keeping your phone in partial wake lock status.

Thanks for that article, very informative, but not necessarily conclusive. There are also a ton of comments that resonate with my concerns, about how random apps I haven't touched seem to constantly start themselves and run in the background doing who knows what - using CPU (battery), bandwidth, whatever.

At least one comment mentioned a significant battery life improvement after installing Advanced Task Killer and turning on its autokill feature, which I've been using a few months. I think I'll experiment a little and turn it off, and see if there's any noticeable difference in battery life.