One of the few books in the O'Reilly "Hacks" range that is worthy of the title, this book covers a wide range of different geospatial topics. The wide ranging shallow approach proves useful as a sampler to identify approaches which might be appropriate for a problem.
Unfortunately, this book is now three years old and is urgently in need of an update - especially for the online chapters.
Yes, a review of another general geospatial book. However, this one has two significant chapters, Mapping on the Web (42 pages) and Building the Geospatial Web (39 pages) dedicated to online mapping. Online mapping is also featured in the other chapters. Subjects are very wide ranging, including GPS topics, simple web site routing, demographic mapping, 3d modelling, and mapping natural hazards. A range of approaches are also covered, although there tends to be a bias towards to open source solutions. It could be argued that this fits the 'hacks' name better, and it is useful to have coverage of systems such as MapServer and GRASS which are usually given less coverage than the offerings from Microsoft and Google. Unfortunately these packages tend to have a steep learning curve. I doubt many people will be able to get MapServer to work with the 15 pages that are devoted to it.
This book does have a use as a sampler. It gives a taste of different approaches to a wide range of different problems. Once you have chosen a suitable approach, you will need to find a different source of information to implement it properly.
The book is now three years old and is in serious need of an update. It has no coverage of KML, Virtual Earth, Google, or OpenLayers!
As a summary, this book could be a useful sampler of different geospatial approaches, but it has limited coverage of many popular online offerings.