Although written around Xcode 3, the content in this book works well with the new, major version of Xcode that Apple released last month, Xcode 4. You may find it helpful to browse through a site I’ve created, dedicated to the differences between Xcode 3 and 4 that may affect you:
The site includes a General Overview of the changes, as well as chapter-by-chapter differences to be read alongside the book.
The information in the posts is mainly screenshots showing what’s different from the figures in the book, and there for if you get stuck. For the most part, it will probably be easy to work out on your own, certainly once you’ve recognized the basic changes in Xcode’s user interface.