We have good news and bad news. The good news is that IBM is exploiting electrons to create memory with 100x the data density we see today. In terms of iPod, that's 500,000 songs. The bad news is that the technology won't be ready for 7+ years. Here's how it works:
In a crude analogy, think of staggered nanowires as roads that, through simple urban planning, create magnetic alleys to store data. Cars/information can race around throughout the entire grid, but it can only park in the alleys. That information can then be read by exploiting the magnetic fields generated by electron spin. Essentially, the entire system is tiny, but there's a viable magnetic signature to track it all.
Also, because we're dealing with such minute forces and measurements, hardware should run quite cool.
The racetrack research team is prepared to build the prototype, which they consider a 3 to 4 year process. Commercial products are then another few years away from that. [bbc]