re: Not sure why you think its a stunt?
Because the engineers working on it told me it was a stunt. This was a heavily modified Dell notebook, with non-production silicon and the ability to turn power saving features on and off in special firmware to see which ones had real benefit, and to see the impact on performance with different settings. The unmodified production version of that laptop (same battery and features) ran 4-5 hours, the prototype ran 8-10 hours, so effectively twice the life with little visible impact on performance. I don't know exactly what is in it, but when they were done, they said the biggest power draw by far was the display. This is a 'big' notebook, 1920x1200 display, not thin or light by any standard.
IMO Intel is doing leadership work in managing the power-performance envelope - the flip side of a big laptop running 12 hours is turbo boost using thermal headroom. They may have gotten a little carried away putting the APIC timer to sleep on server chips in some C states, but they will sort that out...
I have never been impressed with AMD battery life - I had an Acer Ferrari a few years ago which, when new, lasted about an hour on a full charge doing fairly routine stuff. That's about useless if you're not near a plug. Neo is better than that generation, but AMD has a long way to go to get competitive on mobile power management.