As new fabrication and integration technologies reduce the cost and size of wireless sensors, the observation and control of our physical world will expand dramatically using the temporally and spatially dense monitoring afforded by wireless sensor networks technology. Several applications such as habitat monitoring, counter-sniper system, environment sampling, and structure monitoring, have been launched, showing the promising future of wide range of applications of networked wireless sensors. In this talk, I will discuss both the opportunites andremaining challenges we are facing from the perspective of computer systems, including hardware design, operatingsystems, cross-layer design, topology/network management, security and privacy, reliability, and programmability. Finally, I will present some ongoing sensors-related projects at Wayne State University.