From Brewster Kahle at the Internet Archive (archive.org):
“The Internet Archive is now leveraging a little known, and perhaps never used, provision of US copyright law, Section 108h, which allows libraries to scan and make available materials published 1923 to 1941 if they are not being actively sold. … Today we announce the “Sonny Bono Memorial Collection” containing the first books [67 at present] to be liberated. Anyone can download, read, and enjoy these works that have been long out of print. We will add another 10,000 books and other works in the near future … as we automate.”
Which doesn’t mean they can be republished commercially or re-used. For many years now it’s not been safe to assume a starting point of “it’s on archive.org, therefore I can probably re-distribute it”. But still, the new tranches of —1941 books will be very useful for scholars.