With the proliferation of sensor technology and advances in wireless communication, gathering, processing, and querying context information in mobile ad hoc and sensor networks becomes attractive and feasible. To support context-aware applications in such networks, efficient processing techniques for frequently used functionality, such as query and event management, are highly beneficial. In this paper, we discuss the challenges in efficient processing of spatial queries in mobile ad hoc and sensor networks. These comprise advanced query semantics based on inaccurate position information, efficient protocols and algorithms for data storage and query resolution, scalability with respect to network size, and support for mobile network nodes. We outline our concepts for solving these issues and show how they can be implemented in a suitable software architecture. Using current evaluation results, we show that our prototype implementation fulfills the stated challenges.