Responding to Richard Nantel:
Just to respond to the comments, I think there is a very big difference between eBooks and books that are online.
Most books that are online are plain text (as in the Gutenberg collection) or RTF (as are most of the Burgomeister books). These are, of course, free and open access books (whether legal or not).
What these types of books manifestly don't need is a 'reader'. They show up just fine in web browsers, and can even be stored and viewed on MP3 players (eg. Samsung or iPod).
The other types of books online are the scans. This is typically what you would see on sites like megaupload and rapidshare. We are told "All that anyone has to do is go to Google, and type www.rapidshare.com ....the search result will tell you where this file is located to be download" but what you get when you do that is what you get when you search for MP3s - a huge pile of spam sites.
But this leads me to my main point. Mostly, there's no reason to share scans or awkward file formats, like PDFs. Formats that are designed for reading on paper are notoriously harder to read on the web.
Look at the Adobe Max sample, in the image above. Only about a fifth of the screen is devoted to actual text. Were that displayed on my screen (a very nice MacBook Pro, no cheap display) the text would be about 5 point in size, almost impossible to read. Sure, you can magnify it - but at the cost of having lines that extend off the screen to the left or right.
Online, text needs to flow into the available space. This is something PDF and related file formats (not to mention scans) simply don't do. This means you must have very large screens or learn to live with shifting your 'page' up and down, back and forth, a lot.
Text in plain text, RTF and HTML, by contrast, flows into the display window. Narrow the window, and the lines narrow. If there is overflow, it is always at the bottom of the page, allowing a nice smooth scroll (or occasional PgDn buttons).
Above, i read, "For one, it manages all your e-books, sort of iTunes-like, allowing you to easily switch between reading one e-book and another. (Wouldn’t it be cool to have all the learning materials related to a subject accessible through one easy interface?)"
I already have that. It's called the web. I access it using Firefox. I don't even need to store the files if I don't want to (if I want to, I can - and there are numerous content management systems that allow me to manage my text files, or I could simply use the Windows or Mac operating system, which is designed for precisely that).
What we are seeing online is not an increase in the popularity of eBooks per se. We are seeing an increased abundance of free and open content. This is something very different from what the publishers envision.
Book publishers would like readers to use an iTunes-like system - proprietary interface, non-portable content formats, no free or noncommercial content. It's not going to happen, except in some very captive markets. And even in these markets (university and government libraries, for example) the questions are being asked. Why are we paying for this?
This should be noted: "the cost of copying a book and having it put on the internet now runs to about $20 - $30 per." That's not per copy per reader. That's per book. Which makes the per reader cost about 10 cents.
From where I sit, the future of books - properly so-called - online lies not with eBooks, which do badly what HTML does very well, but rather specialty sites like Lulu.com
The book - properly so-called - will remain a print publication, with the bulk of the expense (and the price) being for the paper, ink, binding and distribution. They will be printed for paper libraries (which are still a very convenient place to store information, especially if you have a searchable text version of each printed book), keepsakes and souvenirs.