If you have spoken to me for more than 2 minutes about librarianship, then you have probably heard me say that we live in a hybrid world of both print and digital resources, and that we will continue to do so for quite some time (if not for ever.) The challenge for the early 21st century librarian is to manage the processes necessary to maintain both a print and a digital library and to help our users work in this hybrid world.
Having said that, I do not think that we live in a stable hybrid world. The general direction is of course from print to digital, but there are plenty of retreats along the way (the Rocket e-books being a good example from the 1990's.) If we consider the various formats (for want of a better word) that we deal with -- catalogs, indexes, journals, reference, and books -- and Bill Clinton's "bridge to the 21st century" then we have crossed the bridge from print to digital in terms of catalogs and indexes. Any print indexes or card catalogs left now are just remnants. We are rapidly crossing the bridge in terms of journals. More quickly than I expected in fact and this is true of music as well. We are only just getting on to the bridge with reference books (we still need to solve the problems of OpenURL compliance and federated searching across reference collections) and books in general? Well, I am not sure. I think the printed codex will be with us for a long time. I will be reading one on my death bed and my 14 year old son is a voracious reader of books.
However, I think the traffic on that bridge (to stretch the metaphor way too far) is going in both directions. Books are being created, edited, produced and distributed digitally, but also the technology is impacting the nature of the "book". Our society produced 2-300 page documents because it made economic sense. Creators then tailored their works to that format. In the digital environment (particularly if the reading device of choice is the cell phone) documents -- the packets of information -- may be distributed in much smaller forms. We may buy or access chapter length works, or even paragraphs. You can see this already as what were reference books are now reference databases; like the two most recent additions at the Olin Library: Gale's Literature Research Center and Springer Verlag's Prokaryotes. Both of which also illustrate the amount of work still to be done to truly cross the digital bridge.