GeoPDF is cool
GeoPDF does one thing that nothing else does -- it bridges documents to the geospatial world. It's the one thing that connects that 8 1/2 by 11 (or A4 (or whatever...)) sheet of paper (in its electronic incarnation) to a longitude and latitude that makes sense only if you know that they're tied to Adindan datum.
GeoPDF is the realization of a vision that stretches back to (at least) 1991 -- interactive maps in a portable, printable, reliable, interactive format. That niche in the ecosystem that's growing up with stuff like MS Virtual Earth, Google Earth and Maps is vital and vigorous and it's a wildly exciting place to be.
Note to self: Camelot.