ESTA is a new, fully-automated, electronic system for screening passengers before they begin travel to the U.S. under the Visa Waiver Program. ESTA applications may be submitted at any time prior to travel to the United States, and VWP travelers are encouraged to apply for authorization as soon as they begin to plan a trip to the United States. While ESTA is currently accepting voluntary applications, it is anticipated that ESTA will become mandatory for VWP travelers on January 12, 2009.
Once ESTA is mandatory, all nationals or citizens of visa waiver countries who plan to travel to the U.S. for temporary business or pleasure will need to receive an electronic travel authorization prior to boarding a U.S.-bound airplane or cruise ship. The requirement will go into effect next year and does not affect U.S. citizens traveling overseas.  Customs and Border Protection has published a fact sheet on ESTA, available here: http://Users/davidlewis/Sites/berardi/app/public.cbp.gov/linkhandler/cgov/newsroom/fact_sheets/travel/fact_sheet_esta.ctt/fact_sheet_esta.pdf
White House Announces Seven Countries to be admitted to the Visa Waiver Program: In about one month, citizens of Czech Republic, Estonia, Hungary, Latvia, Lithuania, Slovakia, and South Korea will be able to travel to the U.S. without a visa as part of the Visa Waiver Program (VWP).  Six more are slated as “road map” countries that may soon qualify for the VWP, including Bulgaria, Cyprus, Greece, Malta, Poland, and Romania.  This announcement is a highlight of the ongoing modernization of the VWP.  With increased security measures in place, travel opportunities to the United States are also broadened.
The VWP currently allows citizens of 27 countries to travel to the U.S. without a visa for business or pleasure for up to 90 days.  More information on the Visa Waiver Program found at http://travel.state.gov/visa/temp/without/without_1990.html.