Having done a number of ZigBee kit reviews, I know how hard it is to cover a wide range of similar products. Fred Eady has done an excellent job; I often take cues from it.
Eady does a good job starting with the basics including presenting the range of terms, topics and tidbits that only wireless wonks want to know. Chapter 2, titled You Are Dangerous and You’re Going To Hell, admits that you have picked up enough knowledge to be dangerous, but urges you to keep reading: the best is yet to come.
The next couple of chapters take a look at specific implementations from ZMD and Atmel. These go into detail to highlight how things work with an 802.15.4 system, protocol stack, and all that goes into it.
Then the book goes on (and on) with specifics about what seems to be every vendor on the market. This includes Texas Instruments, Maxstream/Rabbit Semiconductor, Cirronet, Silicon Laboratories, Renesas, Freescale, Panasonic, DLP Design, Microchip and Telegesis.
The one oddity is the Cypress MicroSystems PSoC coverage. It is really about capacitive touch sensor technology called CapSense. It is likely to be found on ZigBee controls because of its low power and high reliability operation.
The accompanying CD includes complete listings of the sample code as well as more details about the ZigBee Alliance. For the latter, definitely check out the website because things are changing all the time in this arena.
I recommend this book to anyone doing 802.15.4 or ZigBee development. It is likely that Eady touches on the platform you are or will be using and it contrasts it well with everything else out there.