This talk describes one of the major efforts in the sensor network
community to build an integrated sensor network system for energy efficient
surveillance.  The focus of this effort is to acquire and verify
information about enemy capabilities and positions of hostile targets.  Such
missions often involve a high element of risk for human personnel and require a
high degree of stealthiness.  Hence, the ability to deploy unmanned
surveillance missions, by using wireless sensor networks, is of great practical
importance for the military.  Because of the energy constraints of
sensor devices, such systems necessitate an integrated energy-aware design to
ensure the longevity of surveillance missions.  In this talk, we
describe the design and implementation of an integrated running system, called
VigilNet, for robust energy-efficient surveillance.  The VigilNet allows
a group of cooperating sensor devices to detect and track the positions of
moving vehicles/personnels in an energy-efficient, responsive, robust
and stealthy manner.  In addition, we will also touch some research issues
on how to use programming abstraction (EnviroTrack) to facilitate the
development of sensor network applications such as VigilNet.