In Krug's book "Don't Make Me Think," he discusses usability. He focusses on several different aspects of usability and illustrates each point with several examples from actual websites. Suprisingly, this book is still very relevant dispite having been written in 2000. Because Krug focusses on general principles, rather than specific trends. He avoids making rules about specific content, but focuses on general content. The point isn't what particular layouts and features are easiest to use, but that whatever layouts and features are selected, had better be easy to use. For this reason the book remains relevant dispite its age.
One possible concern about the book may be that audience attention spans are likely decreasing. However, Krug effectively combats this by suggesting that there is no minimum level of usability for all sites. Instead, Krug suggests that all sites should be as simple as they possibly can be, while still accomplishing their goals.
The only possible update for the book would be a few of the examples. Some of the websites Krug used were a little old, and no longer popular. Some of the ones he used are also older versions of still existent ones. It would seem prudent to include new examples simply because they will seem more relevant to new readers. Really though, there is probably not much point in writing a whole new edition.