Smart Dust sensor networks ? consisting of cubic millimeter scale sensor nodes capable of limited computation, sensing, and passive optical communication with a base station ? are envisioned to fulfill complex large scale monitoring tasks in a wide variety of application areas. In many potential Smart Dust applications such as object detection and tracking, finegrained node localization plays a key role. However, due to the unique characteristics of Smart Dust, traditional localization systems cannot be used. In this paper we present and analyse the Lighthouse location systems, a novel laser-based location system for Smart Dust, which allows tiny dust nodes to autonomously estimate their location with high accuracy without additional infrastructure components besides a modified base station device. Using an early 2D prototype of the system, node locations could be estimated with an average accuracy of about 2% and an average standard deviation of about 0.7% of the node's distance...