Earlier quoted context omitted.
Sorry, but 5 hours on an ultrabook is not competitive. Current Macbook Airs are rated for 12 hours with normal use, and third-party testing has found 10 to be realistic. demallien is right. Nobody on the Linux side has done this kind of aggressive power engineering for consumer-oriented x86 hardware. Google might, for Chromebooks, but it's not clear how portable that will be to the rest of the ecosystem.
Apple states 9h for a contemporary 13" MBP. Mine (two weeks old) runs for 4h max, if I do any serious work on it. If I switch Wifi off an dim the screen, I can get 6-7h out of it. The machine is dual boot as I'm using it to develop software that targets both OS X & Linux. I run a Gentoo with all kernel- and other power saving features enabled, on a 2nd partition. The time I get out of the battery on OS X vs Gentoo is…
IntelliJ however eats some of my battery pwoer, but I still manage 7 hours or full work day.