A blog posting at the New Scientist magazine claims that the USPTO issued secrecy orders on 68 new patent applications and rescinded 47 older orders in the year ending Sept. 30. A total of 5,023 secrecy orders are still in effect. The USPTO reports the number of secret cases in condition for allowance in its annual report, which is usually released in November. The annual report for 2006-2007 states that there were 3,081 such cases as of Sept. 2007.
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.