COMET (Cambridge Open METadata) project was completed this July 2011.
The COMET blog final post sums up the work done, the lessons learned, and indicates some next steps.
The CUL open data service is worth a look. (It is funded under the JISC Infrastructure for Resource Discovery program.)
I was particularly interested in the document on the ownership of MARC21 records by Hugh Taylor, Head of Collection Description and Development at Cambridge University Library. It is nice brief on the issues of intellectual property law and contracts and licences as they relate to MARC21 records in library catalogs. Hugh is very good on "reading the ownership of MARC 21 bibliographic records." The whole project is nicely documented at the COMET project blog.