GPN (Great Plains Network) is a consortium of public universities in seven mid-western states. GPN goals include regional strategic planning and the development of a collaboration environment, middleware services and a regional grid for sharing computational, storage and data resources. A major challenge is to arrive at a common authentication and authorization service, based on the set of heterogeneous identity providers at each institution. GPN has built a prototype middleware test bed that includes Shibboleth and other NMI-EDIT middleware components. The test bed includes several prototype end-user applications, and is being used to further our research into fine-grained access control for virtual organizations. The GPN prototype applications and namespace form a basis for the design and deployment of a robust and scalable attribute management architecture.