Klaus Graf shows that almost none of the research output of the Max Planck Society’s law and humanities institutes (as opposed to its natural science institutes) is OA through the Max Planck eDoc Server. Read the original German or in Google’s English.
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.