If your travel is in less than 2 weeks, and you have proof (Ticket, etc) you can get a same day passport directly from the State Department in certain cities.
http://travel.state.gov/passport/passport_1738.html
Processing time for passports is 4-6 week, 3 weeks for expeditied service
http://travel.state.gov/passport/get/processing/processing_1740.html