Wireless Sensor Networks are a canonical example of a wider field dealing with Cooperating Objects that attempts to create the necessary technologies to make Weiser's vision of the disappearing computer a reality. Cooperating Objects are small computing devices equipped with wireless communication capabilities that are able to cooperate and organise themselves autonomously into networks to achieve a common task. The book contains information about the research roadmap envisioned for Cooperating Objects by the Embedded WiSeNts consortium and its associated industrial and academic partners. The Embedded WiSeNts project started in September 2004 as a Coordination Action funded by the European Commission under IST/FP6 to create a series of studies on the state of the art of Cooperating Objects and to devise a research roadmap to be used for the definition of future research programs. This book is the final result of these two years of work.