My good friend Christina Wodtke (with Austin Govella) just finished the second edition of Information Architecture: Blueprints for the Web and I just finished reading it.
Most of the book is filled with very valuable, basic information about information design for websites, like basic principles, balancing users/technology/business, information organization, navigation and other really important details in designing today's websites. However, the real gems of this edition are the two chapters on search and on social/community design.
Christina is a recognized expert in search. She ran the search UX team for a long time, during a period when Yahoo! feverishly tried to catch up to Google in search. I remember talking to her about all the things they tried and discovered about search, and uncovered about how Google deals with search. Really crazy stuff that is down to the pixel level on how it affects response and the amount of dollars generated. So she exposes some of what she discovered here in her new book; mostly it's about the UX and UI of search which is very relevant and important. I guess you'll have to hire her (and pay her tons of money) to really do a deep dive into how search is tweaked by the big boys.
The chapter on social/community design breaks down the various important aspects of this area of design nicely into parts so that a designer can understand everything easily. It dives into important topics like identity and relationships, and how to manage them. Then it discusses what kinds of activity take place in social applications and how to create a design that encourages activity and doesn't stymie it. Usually we here bits and pieces about how to deal with social sites, but this book just gathers a lot of concepts into one place, which is really valuable.
I'd definitely say this is a "must read" for all information architects both new and old. If you're new to IA for the web, read the whole thing; if you're an old hat, take a look at the chapters on search and social spaces and you'll find that your money is still well spent.
