This report presents results from a case study, conducted as part of Phase II of the Open Annotation Collaboration (OAC), examining nine annotation demonstration experiments and associated use cases. During Phase II, the OAC actively developed and experimented with an RDF-based annotation data model. The primary features of the data model were developed in response to findings in Phase I and evolved during the course of Phase II based on feedback from the demonstration experiments, community discussions, and face-to-face meetings. The case study was based primarily on interviews conducted with project developers and user groups, supplemented with information from final reports submitted by the participating projects.