The eld of wireless sensor networks continues to evolve and grow in both practical and research domains. More and more wireless sensor networks are being used to gather information in real life applications. It is common to see how this technology is being applied in irrigation systems, intelligent buildings, bridges, security mec- nisms,militaryoperations,transportation-relatedapplications,etc.Atthesametime, new developments in hardware, software, and communication technologies are - panding these possibilities. As in any other technology, research brings new dev- opments and re nements and continuous improvements of current approaches that push the technology even further. Looking toward the future, the technology seems even more promising in two directions. First, a few years from now more powerful wireless sensor devices will be available, and wireless sensor networks will have applicability in an endless number of scenarios, as they will be able to handle traf c loads not possible today, make more computations, store more data, and live longer because of better energy sources. Second,a few years from now, the opposite scenario might also be possible. The availability of very constrained, nanotechnology-made wireless sensor devices will bring a whole new world of applications, as they will be able to operate in - vironments and places unimaginable today. These two scenarios, at the same time, will both bring new research challenges that are always welcome to researchers.