Stumbled upon this while looking for something actually useful
(eg. disk drive reliability data -- yeah right). Its more or less
market hype, mainly the forward projections, but the interesting
part are some good drawings of head topology,
density-over-the-ages charts. Good drawing of perpendicular head
design.
IBM by way of Hitachi.
http://www.hitachigst.com/hdd/hddpdf/tech/hdd_technology2003.pdf
It's an ugly old PDF, sorry.