I think Apple is really going backwards with this move.
The platform could have been a great medium to publish (and monetize) any kind of multimedia content (everything that couldn't be considered strictly an application, like interactive fiction, comics, reference books with a customized interface etc).
From an author perspective this could have been a great medium to experiment with. Much more interesting that the kindle or simple e-book reader apps with a fixed user interface.
I see exactly where they're heading: Apple will create their own reader and Book Store in iTunes, where they'll charge content creators 30%. Perhaps if they're feeling particularly generous, they'll let you share your your DRM'd iBooks between your Tablet and your iPhone. Third-party readers are obviously a massive threat to this potential profit stream.
The platform could have been a great medium to publish (and monetize) any kind of multimedia content (everything that couldn't be considered strictly an application, like interactive fiction, comics, reference books with a customized interface etc).
From an author perspective this could have been a great medium to experiment with. Much more interesting that the kindle or simple e-book reader apps with a fixed user interface.