The new issue of Program: electronic library and information systems (vol. 40, no. 3, 2006) is devoted to institutional repositories. All nine articles should be useful to IR maintainers, but the four below are the most germane to my focus here (more on OA to research, less on preservation and technical topics). The journal only provides abstracts free online, though in her editorial in this issue, Lucy Tedd encourages authors to self-archive. (Thanks to Stuart Lewis.)
The open access movement:
Putting peer-reviewed scientific and scholarly literature
on the internet. Making it available free of charge and
free of most copyright and licensing restrictions.
Removing the barriers to serious research.
I recommend the OA tracking project (OATP) as the best way to stay on top of new OA developments. You can read the OATP feed on a blog-like web page or subscribe to it by RSS, email, or Twitter. You can also help build the feed by tagging new developments you encounter.