A new White Paper from the U.S. National Information Standards Organization (NISO), “The Future of Library Resource Discovery”…

“No open access discovery index has been created.” (p.15)

/cough/

[The white paper’s] “review of the [required] components of an index-based discovery service [purely for open access content] highlights the enormous level of resources required to create and maintain them. The creation of an open access discovery index would require the allocation of capital, personnel, and technical resources at least at the level of what any of the commercial providers has devoted to their projects.” (p.21)

Indeed.