I'm a photonics/optics and I find the Xnm figure really fascinating. It is based on a real metric which is the smallest feature size they can make (roughly the resolution of the lithography process). It is absolutely amazing that we have been able to scale things down to image at that level.
Note that with the rise of finFETs we can pull some of those numbers into the 3rd dimension. The effective gate length is higher than the amount of length it takes on the flat plane of the chip.