In this position paper we explore the challenges and issues around interoperability in the web of things. A key concern is how to increase interoperability while maintaining a high degree of innovation and exploration in the community. To that end we propose a hub- centric approach toward interoperability consisting of four levels or stages. We are working to validate this approach in the context of a large-scale IoT ecosystem project consisting of eight IoT hubs in different domains where a key requirement is hub-to-hub and hub- application interoperability.