The cat's out of the bag now – Apple is taking on publishers and publishing. The new iBooks Author application for the Mac (via the Mac App Store only) allows authors to directly create ebooks and sell them through the iBookstore, no publisher required. It's part of the technological revolution that's been going on for decades; just as we can now type for ourselves, do layout and spreadsheets ourselves, record music ourselves, alter pictures and videos ourselves, and write apps ourselves, now we can write and distribute our own books.
The question remains, what of publishers? Is there a place for them anymore? It's easy to see this as an attack on publishing houses, that they have been disintermediated somehow, but I'm not so sure. We will always need some sort of gatekeeper for material, especially if the iBookstore takes off and ends up with lots and lots of titles. How will we separate the wheat and chaff? Will customer reviews cut it? I think not, that we'll still need editors for our material who can be imprimaturs for quality. Cambridge University Press will always stand taller than Joe Bob's Real Good Books, and it importantly vets books in terms of quality, writing, and subject material. We will also need advertising and promotion, which is something publishers can do quite well.
The problems for academic publishing, in relation to iBooks Author, are prestige and libraries. I don't see anyone quite filling the niche of the publisher that throws its weight behind a subject and title, and the prestige that academicians require in terms of their publications. Self-publishing is a harder row to plow; it's rare that a self-published book reaches academic fame. Further, there is the all-important university library that buys and makes available important (and increasingly expensive) books. Libraries also play an important vetting process as they choose books available to current and future students and researchers. University libraries have little role to play in the iBookstore, as far as I can see. The iBookstore is for individuals only, and this will limit its academic impact, since so much of academic research is done in libraries and with shared resources. Managing a solitary library sounds, well, expensive and difficult.
This is not to say that some individual scholars might not self-publish, through the iBookstore, with great success, but they will be the rare ones, the Bart Ehrmans and Terry Eagletons who can cross between academic and popular appeal, and the problem is establishing that authority and acclaim. I think a scholar would have to have success in a public way, such as an important blog or media presence, in order to then have name recognition and then success on the iBookstore. Otherwise, well, you're on your own.