Sensor networks will be an important part of our life in the near future. From natural monitoring to ambient awareness, from battlefield to surveillance and security, a plethora of applications can be developed based on the availability of mechanisms to extract information from the environment, process it, and put it to good use. Beyond the original motivation of early research projects, interest in sensor networks is becoming pervasive, and the variety of fields of application is just enormous. A key feature of these networks is the need for self-configuration and self-maintenance, and the extreme resource poverty of their individual elements in terms of energy, CPU power, memory, and so on. In this context, it becomes challenging to provide effective solutions because of the severe and untraditional constraints that must be taken into account. It is also interesting to study these systems since many new trade-offs can be identified in the design space that do not play a significant role in traditional networking. Also, in order to provide effective solutions it is necessary to take a very interdisciplinary approach and face the challenge of both asking very fundamental questions and building real systems to test ideas and insights.
      At a time when sensor network research is flourishing, and many new insights and techniques are being proposed and understood, it is very appropriate to have a special issue of our magazine on this topic, which may serve as a starting point for people to get excited about the area and want to know more, as well as a chance for people already active in the area to have a recent snapshot of what is going on in this field. While an exhaustive review of sensor networks research would need much more than a single issue of the magazine, I think our readers will appreciate this collection of papers and join me in thanking the guest editors (Paul Havinga, Jennifer Hou, Mani Srivastava, and Feng Zhao) for organizing and handling this special issue.