There is a new address for the USPTO's customer window that receives hand deliveries and non US Post Office (USPS) deliveries. (Effective June 5, 2004)
U.S. Patent and Trademark Office
220 20th Street S.
Customer Window, Mail Stop ________
Crystal Plaza Two, Lobby, Room 1B03
Arlington, VA 22202
The Customer Window is the delivery location for patent-related correspondence to be hand or courier delivered to the USPTO by delivery services such as FedEx, UPS, DHL, Laser, Action, Purolator, etc. The customer window is not used for correspondence delivered by the United States Postal Service (USPS).
More PTO Address Info here.