The Web is pervasive, increasingly populated with interconnected data, services, people and things [6]. As stated in [7], the Web is the middleware of choice for most distributed systems, where hypermedia turns into a homogeneous information fabric that interconnects everything — devices, information resources, abstract concepts, etc. Clients are not only able to browse and query, but also to observe and act on this hypermedia fabric, transforming the Web in a sophisticated social machine [3]. The next step, which has been awaited for a long time, consists in bringing in this global ecosystem, autonomous agents, entities able to react to events while pro-actively defining goals and directing actions to achieve them. Using this hypermedia fabric in a flexible and autonomous manner, agents will build hybrid communities on the Web [2], where they will help people cope with the growing number of available resources, and achieve increasingly complex collaborative tasks.