There is a STEP-UP in profits following each geometry migration. The number of die sites on a wafer increases geometrically (smaller rectangle dies on the surfaces of a circle) while the wafer processing cost increases linearly.
The migration to 22nm will benefit from this same linear/geometric relationship. The migration to 22nm will also benefit from the additional 3D effects.
Server chip performance (cores, cache size, ...) is currently limited by the "power dissipation envelope". Cooling the chip is the limit to the cores, frequency, transistors on the chip, ...
3D enables more transisters in the same nano-acre of silicon. 3D enables lower power which will translate into more cores, cache, frequency for server chips. 3D enables lower voltage which will open up tablet, smart phone sockets.
There is the historical step function in earnings at the 22nm migration. The interesting thing is the 3D density/power multiplier on that earnings pop.