The NIH public-access policy has substantially increased public access to research results with benefits as described below that far outweigh the costs. Similar benefits can be expected from extending such a public access policy to other major federal funders.
from Committee for Economic Development, The Future of Taxpayer-Funded Research: Who Will Control Access to the Results? issued last week.
The question, of course, is who pays to maintain the archive? OA really has to get past that burden