Lev Grossman argues that we are losing non-linearity in the shift to ebooks:

We usually associate digital technology with nonlinearity, the forking paths that Web surfers beat through the Internet’s underbrush as they click from link to link. But e-books and nonlinearity don’t turn out to be very compatible. Trying to jump from place to place in a long document like a novel is painfully awkward on an e-reader, like trying to play the piano with numb fingers. You either creep through the book incrementally, page by page, or leap wildly from point to point and search term to search term. It’s no wonder that the rise of e-reading has revived two words for classical-era reading technologies: scroll and tablet. That’s the kind of reading you do in an e-book.

The codex is built for nonlinear reading — not the way a Web surfer does it, aimlessly questing from document to document, but the way a deep reader does it, navigating the network of internal connections that exists within a single rich document like a novel.

This is a very interesting, if odd, argument to make. I’ve always assumed that digital is as non-linear as they come. But Grossman may be wrong — he’s assuming that the methods for navigating an ebook will always be lousier than that of navigating a codex. That may yet change.