I can highly recommend this book. It will stay on my bookshelf for years as my de-facto reference book for mobile application technologies.
The mobile data world is in a rapid transition from text to multimedia and 2g to 3g. This book will allow you to understand the capabilities available for service creation and delivery. If you are involved in developing, delivering or marketing mobile applications and services this book is a must read.
All of a sudden I know what the techies are talking about :-)