With its deal last month to provide search services for airplane makers' WiFi service, Yahoo's 100,000 advertisers can reach travelers on China Airlines, Lufthansa, SAS, Japan Airlines, ANA and Singapore Airlines. Five more, none of them U.S. airlines, have said they want to install the system, reports AdAge (via MediaBuyerPlanner).

According to Jupiter research director Julie Ask, in-flight hotspots are a way for airlines to differentiate themselves. If business travelers are paying thousands of dollars for an international ticket, they likely wouldn't blink at the $9.95 per hour fee - and airlines really need reasons for travelers to select them, she said.

Lufthansa said 10 passengers per flight use the WiFi connection.