
Um...possible new wrinkle...
Some guy named Russel has posted a review over on Amazon in which he refers to PoD as "the first half of a longer book", to be completed by Jessica of Dune. That doesn't jibe with anything I've seen mentioned by the Hack or Byron, but it kinda makes sense if you think about it.
Originally they announced a trilogy, to mesh with the originals like this:
Dune
Paul of Dune
Dune Messiah
Jessica of Dune
Children of Dune
Irulan of Dune
God Emperor of Dune
PoD was to come out this year, with the other two books each coming two years later, because they'll be releasing one of their Hellhole trilogy books in the off years. PoD was included in the same contract as Hunters and Sandworms.
When they signed the contract for the next two books this year, they suddenly releaved a fourth book, Leto of Dune, to cover the first years of Leto's reign, and started talking about releasing Jessica next fall, instead of autumn 2010 as originally announced. That would mean something like this:
Dune
Paul of Dune
Dune Messiah
Jessica of Dune
Children of Dune
Irulan of Dune
Leto of Dune
God Emperor of Dune
I'm wondering if what they're really planning now is this:
Dune
Paul of Dune
Jessica of Dune
Dune Messiah
Irulan of Dune
Children of Dune
Leto of Dune
God Emperor of Dune
(Edit: This IS what they're planning.

A bad precedent, IMHO. If they start squeezing multiple books in between the originals, there will literally be no end to them. The ten-volume Duncans of Dune would fit nicely between LoD and GEoD, no?

This is all speculation based on what may be a simple error in a review on Amazon. But neither KJA nor Byron have ever even referred to much less explain the change in publication schedule for JoD or why LoD was suddenly added.