Kate Price has posted a summary of the responses she received to an informal survey she did on JISC-REPOSITORIES about the use of institutional repositories and central publications databases. Responses are broken down into five models (e.g., "operates separate open access repository and central publications databases") and by system (e.g., EPrints).
In a related message, David Groenewegen points to the ARROW HERDC Working Group Interim Report May 2008.
Here's an excerpt from the report's "Introduction":
This report is an interim report on the activities of the Working Group. The interim report aims to stimulate discussion and invite feedback which will inform the final report.
As a first step the Working Group has identified and developed four potential broad models to represent the relationship between the university's research management system and the institutional repository.
The purpose of these models is to suggest possible workflows and processes, to stimulate discussion, and to identify the strengths and weaknesses of each approach. It is assumed that local use of these models will necessitate variants as required by the environment of each institution.