Advance copies of regulations, called "public inspection documents" are actually published on the FederalRegister.gov website *before* they are formally published in the Federal Register as a publication.

Basically, all agencies are required to make their new rules available for physical public inspection somewhere -- like a desk or filing cabinet somewhere in Washington, DC. The Office of the Federal Register takes care of making these physically available, but there's nothing stopping them from simply digitizing these documents and publishing them online too -- so that's what they do.

FederalRegister.gov is an amazing website, with an amazing story - it was built by a team of citizen developers that first built an unofficial version, GovPulse.us, before they were contacted by the Office of the Federal Register and asked to make it official. They are also a prolific and restriction-free data provider, and we make use of this to tie advance copies of regulations directly into Scout.

You can read more about this on our blog:
http://sunlightfoundation.com/blog/2012/07/11/getting-the-jump-on-regulations/