The globalization of businesses and the cooperation between organizations have brought on an ever increased need for providing support for distributed collaborations. In this paper, we argue that existing peer-to-peer frameworks, although suitable for collaborative environments, fail to provide the support for multiple consistency semantics required by modern complex collaborations. We present GRACE, a middleware platform that enables distributed and mobile collaborations, by combining the capabilities of Distributed Hash Tables (DHTs) with a layered architecture that supports a wide range of semantics. The DHT substrate provides support for mobility, high scalability, availability and load balancing of data, as well as self-repairing capabilities and ease of management, while the layered architecture takes into account the different semantic needs of the applications. We evaluate the efficiency of the algorithm for routing requests to the correct replica in an implementation of GRACE built on Pastry.