Today it was announced that Amazon's sales of e-books for Kindle in the US surpassed their sales in paper copies during the last three months of 2010. In socio-economic terms, the book (or more precisely, paper) is now largely obsolete as a format for information transfer. In society, information interactions of immediacy are conducted electronically (whether or not they are retained in hard copy for preservation purposes is another matter). In our economy, well, information interactions of immediacy are the economy.
In the final analysis, a paper document as a format for information transfer is analogous to any other largely obsolete format, such as vinyl records, or the cassette tape. Vinyl, in particular, has a unique quality to be sure, and can arguably enhance the listening experience. Similarly, reading a paper document is often far more comfortable for many. But this isn't the point. If you hear a new song you enjoy these days, you're unlikely to hit the record shops, much less purchase a vinyl record - you'll probably search YouTube and, if you like it, download the track in one way or another to a digital device. Even from the angle of comfort or nostalgia, Amazon's example proves that attitudes are changing.
Going back to the point on preservation: where a retroactive decision is made to preserve a document, common sense still indicates that this will need to be hard copy; the digital preservation challenges of storage, migration, emulation &c. have yet to become either simple or reliable. This is why the book, or paper, is literally history - it's a tool for engaging with the past, and a critical one, but no longer common currency for an information of immediacy. The book as a social and economic force has had its day.
Despite the fact that I invest time in exploring digital technologies, it is difficult to keep pace. I've just noticed that, in the few years between my current degree and the last, hard copy submissions of coursework are no longer accepted (at least at my university). In prioritising traditional models in the information sciences, this could have a detrimental impact on an institution's capacity to deliver information, turning what purport to be centres of current knowledge into museums very quickly indeed.
I suspect that the principal reason why some still give books so much currency in a digital world is because they've had such an unusually long run of dominance as a format. Even before the codex, there was the scroll and the bamboo fragment, and a clear chain of technological development can be traced from antiquity. But an appreciation of books for their own sake is not something that many people in the world have the time or money to share in. While digital technologies carry the potential for a digital divide to further separate develop and developing economies, or even citizens within a single country, there's also the huge potential to leap-frog dated communications technologies and create education initiatives, in particular, that could never have been possible before. More on that later.