If beauty is in the eye of the beholder, then usefulness must be in the hand of the... of the... Hm. I bet that if I could come up with the right noun, that saying would catch on.
Anyway: if you're involved in open source software in any way, shape, or form, then Open Source Licensing is a very useful bunch of nouns (and verbs, and adjectives) to have at hand. Its author, Lawrence Rosen, is intimately familiar with the field: among other things, he's general counsel of the Open Source Initiative. In this book, he lays out a general background for discussion of intellectual property, and the history of free/open source software, then discusses what various popular licenses actually mean. The book closes with chapters on topics such as how to choose a license, litigation, and standards.
Rosen's writing is clear---exceptionally clear by legal standards---and he takes time to explain terms and assumptions that most software developers won't have encountered before. What's more, he doesn't seem to have any particular axes to grind: the book is US-centric, but his treatment of the various options open to today's developers is very even-handed. Taken as a whole, this book is a good complement to Fogel's Producing Open Source Software, and would make a great companion text in a course on software business and ethics.
In contrast, Peter Morville's Ambient Findability is---well, I'm not quite sure what it is, but the term "useful" doesn't leap to mind. Morville's topic is an important one: how can we help people survive the information tsunami we all now live in? How can we help them find what they need, without drowning in trivia and distractions?
Unfortunately, while this book throws a lot of ideas into the air, it seems content to then stand back and say, "Oooh... pretty." There's little practical advice; instead, we get Figure 5.1 (which uses the yin/yang symbol to illustrate push vs. pull) and a lot of reminiscing that never quite seems to yield a plot line. Perhaps I'm just the wrong whatever-the-noun-is for this book.
Peter Morville: Ambient Findability. O'Reilly, 2005, 0596007655, 188 pages.
Lawrence Rosen: Open Source Licensing: Software Freedom and Intellectual Property Law. Prentice Hall PTR, 2005, 0131487876, 396 pages.