Looks like at least one library is trying a variation the method I suggested...
"The Patriot Act also prohibits libraries and others from notifying patrons and others that an investigation is ongoing. At least one library has tried a solution to "beat the system" by regularly informing the board of directors that there are no investigations. If the director does not notify the Board that there are no investigations, it can serve as a clue that something may be happening. "
http://www.ombwatch.org/article/articleview/1706/1/41
http://librarian.net/technicality.html is another example if such tactics.
--B