The USPTO has made available scanned copies of all editions and revisions of the Manual of Patenting Examining Procedure (MPEP) from 1948 forward. Previously, only the most recent editions were available online. This collection will be useful for locating historical information on US patent documentation, numbering systems, classification and prior art rules.
I'm the librarian for research services in the Engineering and Science Library at Queen's University in Kingston, Ontario. I've been working with patent information since 1991, including seven years at the U.S. Patent and Trademark Office. I believe that the dissemination of patent information is a public good and should be promoted, especially in the education of science and engineering students.