A flexible Wireless Sensor Network platform for easier implementation of diverse applications has been developed and deployed at the Instituto Superior Técnico - Technical University of Lisbon (IST-TUL). This test-bed integrates multiple projects into a single common network, thus creating an expandable platform that facilitates the development of future applications. To achieve this flexibility, a dedicated software framework was developed that not only provides a centralized configuration panel that is accessible over the Internet, allowing the administrator to configure common network parameters, but also supports application programmability, enabling fine-grained control of in-network sensing, processing, and actuation. On top of this platform, three initial applications have been developed and are currently coexisting within the same network, thus demonstrating the new platform’s capabilities. The paper discusses the main issues related with the test-bed architecture and the development of an environmental interaction application, with an illustrative purpose, along with the deployment challenges. Results of the experimental evaluation of the test-bed are also shown, focusing on the performance of the environmental interaction application’s in-network processing system. A particularly relevant result is denoted by the minimum time the network needs to complete its processing tasks (approximately 200 ms in our test topology).