-SiliconAddict
One additional advantage of getting the bits so much closer together by standing them up on the disk is the seek and transfer times decrease inversly with the increased density. Meaning that a 4800rpm drive that has twice the density of another 4800rpm drive has about half the seek and transfer time - more bits over the head at a given time.
This has the additional benefit of not needing to up the speed, therefore preserving battery times. But what we're looking at is a 10x-100x increase in density as 100grains that are used to record a bit can be 'stood up' and therefore take 1% the space (ideal world, of course). So that can mean that it's conceivable that a drive could get the same performance as today's while running at 48rpm (barring all that space, of course).
I'd love to see the battery time on that.