Although there has been little industry noise about Phase Change Memories (PCMs) and no revenue stream, that has not deterred IBM's 'Deep Research'

Follow up:

from another announcement in the NY Times, recasted in the local San Jose Mercury News about IBM's progress in hyper-dense memory technology possibilities of more than 100x times those of current hard drive densities and solid state memories (i.e., NAND flash), to more than 1M MB per square inch. The technology underlying these hyper dense and hyper fast storage media is one its developer Stuart Parkin, 'Father of Giant Magneto Resistive (GMR) technologies for hard drives, calls "Racetrack Memories", which not only can reduce the size of the magnetic storage elements currently seen in HDDs, but can read and write data many hundreds of times faster than existing methods.

His idea, as described in the news article is "to stand billions [!] of ultra fine wire loops around the edge of a silicon chip...and use the electric current to slide infinitesimally small magnets up and down along each of the wires, to be read as digital ones and zeros."

Sounds like science fiction, but maybe not. See:

http://www.nytimes.com/2007/09/11/technology/11storage.html?ref=technology.