Tezzeron Semiconductor had first done stacked silicon with connecting vias years ago. They actually are in limited production with a stacked memory part. They also demonstrated a stack with a uP, memory and controller all together. They can stack up to 30 wafer layers at a time.

I christen it "The Club" after your comment of it resembling a "Club Sandwich".
I hope theres no trademark infringement with any product endorsed my "Tonya Harding".

hmmm club sandwich ,,, drool

Heat may not like going through so many layers so they had to keep the thermals under control. This will also contribute to the claim of being more energy efficient not because of the stacking but by necessity of successful stacking.

technical term, when you put one chip
on the back of the other, was called
'piggy-back' back in the days..

The term "chip butty' might be a bit working class for the lofty aspirations of the semiconductor industry, perhaps "Chip Club Snadwich" would gain more acceptance.

Of course the real breakthroguh won't occur until someone invents the "Chip California Sushi Roll"

..thru-silicon-via technology. They build on the stacked-die concept which conventionally allows only 2-chips to be stacked.

It's simply called a "stacked die" assembly, and they've been around a while now in the realm of mixed signal devices.

The idea of skewering them together is neat, though.

you chaps might need to a little more research. There are atleast 6 companies who have been doing this for more than 5 years with commercially availble, high volume products.
Keep up the good work!
all the best, Ashe