JISC has released Machine Services for Metadata Discovery and Aggregation—metadata+.
Here's an excerpt from the Executive Summary:
The main aim of the project is to develop an interoperability demonstrator to explore the technical aspects of providing a service-oriented infrastructure to facilitate metadata discovery and aggregation. The project developed a test bed that exposes metadata through standard search and linking protocols. Metadata mapping work was undertaken to enable the test bed to provide search response in multiple metadata schemas that are widely used in digital library and e-learning.
The core of the test bed consists of an open source digital repository—Fedora. Off-the-shelf, the repository provides web services for metadata searching and substantial content management and security features particularly suitable for real-life use scenarios. Since the search protocol considered in this project requires additional features that are not available from the repository, modifications to the repository source code were made. The modifications also involve incorporating the metadata mapping requirement such that search responses from different metadata formats can be facilitated.
A basic demonstrator (project website) has been created to exemplify how the search protocol can be used for discovering and aggregating metadata, as well as presenting them in coherent formats relevant to the intended presentation contexts. The metadata sources include publisher and digital libraries providing both bibliographic and user-generated (enrichment) metadata such as reviews and recommendations. In addition, the project demonstrated a novel use of the search protocol to dynamically create e-learning content packages, digital library metadata collection and news feeds.
Several digital libraries initiatives have evaluated the test bed infrastructure for real use scenarios. These libraries are an extended form of the test bed demonstrator and provide relevant facilities such metadata wiki (editor) and annotation services for gauging enrichment metadata (review, rating and recommendation) from users. They will continue the objectives of this project particularly on improving the test bed infrastructure and exploring the aggregated use of enrichment metadata, to enable the academic and research user communities to add values to bibliographic metadata from the publishers and libraries communities.