American Airlines and AirCell announced this week a plan to launch in-flight WiFi service on intercontinental flights in 2008 after a testing period.  The service, reported Wednesday, will use AirCell's air-to-ground network. Passenger testing will be conducted on American Airlines' fleet of Boeing 767-200 aircraft.  AirCell, a provider of data and voice communications on business jets, purchased spectrum for its service after Verizon Communications gave up its seatback Airfone system.