A new generation of applications that consist of dozens to thousands of tiny processing units is emerging, called pervasive computing. Potential applications include machine health and diagnostics, physiological monitoring, environmental monitoring, asset and inventory management, smart agriculture, and many more. The key enabling technology for these applications is the advent wireless sensor networks that merge ultra-low-power communication with miniaturization of sensors and actuators. In this paper both the benefits and the many new challenges for embedded system engineers are discussed.