The U.S. Copyright Office is proposing a rule change for the mandatory deposit of electronic works that are published in the United States and are only available online. (Thanks to ResourceShelf.)
Here's an excerpt from the notice of proposed rulemaking:
The Copyright Office of the Library of Congress is proposing to amend its regulations governing mandatory deposit of electronic works published in the United States and available only online. The amendments would establish that such works are exempt from mandatory deposit until a demand for deposit of copies or phonorecords of such works is issued by the Copyright Office. They would also set forth the process for issuing and responding to a demand for deposit, amend the definition of a "complete copy" of a work for purposes of mandatory deposit of online-only works, and establish new best edition criteria for electronic serials available only online. The Copyright Office seeks public comment on these proposed revisions.