Probably the definitive hobbyist’s description for small-scale sensor networks.
This was one of the first non-academic books on sensor networks, complementing other O’Reilly titles dealing with the Arduino. Faludi describes the basics of Arduino programming, XBee radios, and sensor electronics, with several example projects and a lot of humour. The book is really a pleasure to read, but more than that, it’s an easy-to-follow and accurate walk through the technology from the perspective of a practitioner wanting to get started. A lot of the basics on this site — XBee radio set-up, for example — owe a great deal to this book. Faludi’s blog and web site is also a good source of news and ideas.
Faludi covers Arduino-based systems, but also the use of XBee radios “bare” without a microcontroller, which would be of interest for anyone wanting to do a really minimal sensor suite: the radio can take samples itself and send them to a co-ordinator without an external microcontroller, so just deploying the radio with some sensors soldered on is a possibility. (Personally I’ve never found the need, and the additional flexibility of a general microcontroller is almost always welcome.)
For a software person, the main point of this book is to change your perspective away from everything being in software (including the radio protocol stack and the like) to the embedded systems world where modules are more functional and the general microcontroller is simply co-ordinating between other functional units.
As with other O’Reilly titles, you can buy a print copy, on-line access, or a downloadable PDF or e-book, depending on how you like your reading material. The “e-” formats are perfectly readable and save shipping, handling, and desk space.