Tuple Spaces offer a coordination infrastructure for communication between autonomous entities by providing a logically shared memory along with data persistence, transactional security as well as temporal and spatial decoupling — properties that make it desirable in distributed systems for e-commerce and pervasive computing applications. In most Tuple Space implementations, tuples are retrieved by employing type-value matching of ordered tuples, object-based polymorphic matching, or XML-style pattern matching. In a heterogeneous environment, this can pose several limitations. This paper discusses the architecture and implementation of a prototype semantic infrastructure, which uses Semantic Web technologies to represent and retrieve tuples from a Tuple Space. Semantic Tuple Spaces (sTuples) overcomes limitations of the JavaSpaces Tuple Space implementation, by making use of a web ontology language and RACER, a description-logic reasoning engine. The sTuples infrastructure extends and integrates with Vigil, a secure framework for communication and access of intelligent services in a pervasive environment. Specialized agents, such as the tuple-recommender agent, task-execution agent and publish-subscribe agent, which have a better understanding of the environment, reside on the Tuple Space and play an important role in providing user-centric reasoning.