I had also figured it would be fantastic to shrink the shelf space for tech books, and always have those books at hand. Big downside that doesn't hit you till you try to use it for this purpose: the e-ink can't page flip fast enough to be useful.
Readers on the iPad (iBooks, even Kindle app) don't have this issue.
I prefer e-readers (Sony Reader, Kindle DX, iPad) because I read at the speed of about one airport novel per hour, meaning I need five books for a cross country flight. It's easier to carry these electronically, and I keep a backlog of 50 - 70 books available to read.
For computer books, such as the jQuery Cookbook I purchased yesterday from O'Reilly in this sale, I will also read each one from cover to cover. With that reading I form a visual spatial memory of where in the book I can find any information I need.
My memory is not eidetic. I can't read the actual words, and I don't remember every page number. But I do know about how deep in the book, left or right page, and where on the page to look, so I can usually find a needed reference within a half dozen page turns.
With e-readers, this is fuzzier. The "where in the book" depends on the progress bar, and there's no left or right to halve the search, so takes at least 10 - 20 page turns instead. These page turns are SLOOOOOW.
On the iPad, page turns are many times faster. So, finding reference material in a thick reference book that I cognitively mapped on the iPad is commensurately faster.
I usually trip up on the "induct on n" part. Fortunately, I start enough books that I still finish a few each year.
I usually trip up on the "induct on n" part.