While it's a great and interesting blog, I must take issue with the statement, that: "... It's no surprise to the average e-book enthusiast that PDF's fixed-page nature makes it a poor e-book format...."
Not true. I don't know who the "average" is, but the most recent poll I remember linked here, indicated that PDF was the choice of about HALF of the e-book enthusiasts who responded, with the rest divided among the myriad formats bickering for attention. And this was after an orchestrated campaign here to skew the poll, and have MR users go vote for EPUB.
On a large screen, a PDF can be by far the most robust format, both for very complex pages (think fashion magazine), and for simple (but still formatted) text. It can handle color well, too.
For smaller screens, PDF is still great, as the new mobile SDK can reflow.
This has been discussed before, and while at first I was not certain, now I am sure that PDF is by far the most versatile format, with the best potential longevity, since it can scale with advancements in hardware.
If someone wants total control over their text, why not just stick with plain text files, and be done....
Finally, because of the nature of manufacturing, screen sizes will standardize, just like they have done so for laptops and monitors. So, in reality, fixed size is not such a problem, for most.
And for those who enjoy micro editions (screens), PDFs look as good as it gets on the Iphone.