[axiolite]

There's nothing special about PDF. Only reason PDF is useful is because it's easy to convert to/from Postscript and Adobe was pushing out a free viewer for PDFs but not Postscript files. That, and the difference in fees they chose to charge on the formats.

[Finnucane]

That may be true, but it is so deeply embedded into publishing workflows now it would be hard to dislodge.