CNI, Mellon, Microsoft, JISC and DLF sponsored a meeting a while ago to discuss repository interoperability. The report of the meeting has just been published [pdf]. This will be of interest to folks interested in how stuff moves between repositories, and it is likely that there will be followup work looking at some of the directions suggested.
This meeting confirmed for me the need to think about repositories as collections of services on managed objects. Here is how I characterized this view a while ago:
We are moving away from thinking about a repository as a 'bucket' into which we pour content. And towards a sense of repository as a set of services on managed objects. Different repository frameworks might provide different services in different configurations. [Lorcan Dempsey's weblog: Repositories ain't what they used to be ...]