Re:what this actually means (Score 1)

One of the newer tricks (er, relatively speaking - early 90's) in magnetic memory is using Giant Magnetoresistive materials in the memory cell. The polarities of a sandwich of various layers of GMR stuff actually causes a change in resistance which you can check on by comparing to a reference cell (if 2 layers are polarized so that the moments are parallel, the unit has a lower resistance than if the polarities are antiparallel). I'm not sure if IBM is gonna use a pseudo spin valve or a magnetic tunneling junction as the base of their cell design, though. That article was pretty vague. In any case, some designs do have non-destructive read out, so you don't have to rewrite after reading. Lots of tasty research papers have been written on the subject, so go visit your local college library for details.