Kindle model is very similar to Apple and iTunes
I believe it can can display PDFs, in the same way that your ipod can play MP3s.
Kindle integrates very nicely to the Amazon store and lets you buy books in their own DRM'd format very very easily... at a mainly fixed price.. again, this is sounding quite familiar.
I can't believe Amazon haven't looked at Apple when building this setup. I wouldn't have thought Apple is too fussed about other people selling books for less. What they care about is that they are the easiest option. Sure you could save a dollar or so hunting about, but I want it now *click*
And once again, once people have got their pile of Kindle-chained reading material they'll be on kindles for the rest of their lives. They'll buy their children/spouse a Kindle so they can share books (ebook sharing is not because they like us).
You buy a Kindle now. A nicer device comes along - your electronic library going up in flames isn't going to make you wish to switch.
This is still just the start of the market though. As with downloaded music, we'll get the waves of rival devices, rival stores - until the point where everybody has an ebook reader and their given away pennies. We'll then have the backlash against the DRM kicking in. Then the disruptors will wade in and the DRM will start to go away once more. For example Amazon now let you buy from them, at less than iTunes and it seemlessly adds itself to your itunes (and therefore ubiquitous iPod). It'll take a few years - but all these devices will start opening up again.