If a U.S. government shutdown takes effect on October 1, 2013 the U.S. Patent and Trademark Office will continue most of its usual operations. According to the USPTO:
In the event of a general government shutdown on October 1, 2013, the United States Patent and Trademark Office will remain open, using prior year reserve fee collections to operate as usual for approximately four weeks. We continue to assess our fee collections compared to our operating requirements to determine how long we will be able to operate in this capacity during a general government shutdown.
If the shutdown extends beyond the time for which the USPTO holds reserve funds, it may suspend most operations at that time.
UPDATE 10/2/13: Although the official word from the USPTO is “business as usual” the Office isn’t completely untouched by the shutdown. For example, the USPTO cannot respond to requests for paper copies of archived files during the shutdown, because the USPTO’s archive is located at a General Services Administration (GSA) warehouse that is temporarily closed. In addition, the USPTO has cancelled its 18th annual Independent Inventors Conference, which was originally scheduled for October 11 and 12.