The new issue of Library Hi Tech is devoted to the Open Archives Initiative Metadata Harvesting. The guest editor Timothy W. Cole. Only abstracts are free online. Here's the TOC.
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.
