The new NIH policy about open access will begin to be implemented on April 7, 2008. So, April 6 is a good time to collect baseline data about the portion of the literature that’s a result of NIH-funded research. ...
[P]ercentages of publications identified in PubMed as freely accessible were:
Published within the last 2 years: 45361/145354=31%
Published within the last 90 days: 1039/11905=9% ...
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.
