IBM's "3D system prototype of an eDRAM cache stacked over processor-like logic using through-silicon vias": Like the other two chips, the IBM prototype routes data, clock, and power signals through its layers – what IBM calls "strata" – by means of through-silicon vias (TSVs).
TSVs are essentaily just what they sound like: signal paths that are etched through a silicon layer and filled with a conductor. In IBM's prototype, the TSVs are copper-filled, and are about 20 micrometers (0.0008 inches) in diameter."
"These are single parts with processor and memory closely coupled, married together in a single slab."
thats a bit crap for 2012 ,they couldn't even bother to use a real CPU core, or even add an incredibly thin Nano-coating of alumina to the metal interconnected surfaces to double rate of heat transfer, never mind actually adding some generic cheap nano thermoelectric efficiency to the parts to recycle generated heat back into usable internal power for the ram rails, D'oh.
next they will be saying they cant add a few "Nanoshell whispering galleries layers of Nanocrystalline-silicon (its is a great photovoltaic) to to the top surfaces so capturing and absorbing more light gradually by the silicon and so add even more free electrons to add the to whole local re-cycled power budget, to start with..... :)