Most applications, etc. don't have a support forum, only a mailing list or sourceforge project, so it's more difficult to get help
You are absolutely right there, I have quite a few programs installed that are like that!
Battery life is of zero importance to me though, in fact my laptop doesn't even have a battery, just an empty slot at the back where it used to live, that is why I have never heard of Jupiter. I must admit it looks quite a useful tool if battery life is important to you.
You are probably right that Linux doesn't have functionality like that built in, I don't know because I have never looked for it. If I have a problem at all with power management on Linux it is the opposite of yours - trying to make things stay on when they keep going off, not the other way around. As you might have guessed my laptop is a desktop replacement and is plugged in all the time.
Given those differences in our usage patterns I probably can't help you with this, sorry.
Fujitsu Lifebook AH532. Intel i5 processor, 6Gb ram, Intel HD3000 graphics, Intel Audio/wifi. Realtek RTL8111/8168B Ethernet.Lubuntu 13.10,Ubuntu12.10 (Unity), Mint16 (Cinnamon), Manjaro (Xfce).