NEW YORK: This morning, barely a week after Delta officially released the name of its low-fare subsidiary Song, JetBlue Airways has retaliated by unveiling its 37th aircraft, named "Song Sung Blue.""It's a rather cheeky response," said JetBlue VP of corporate communications Gareth Edmondson-Jones. "The message is that we hear you coming, but you can't copy us. You can copy the bells and whistles, but you can't copy the spirit." Announced on January 29, the Song brand is intended to compete with JetBlue, targeting a young audience with low fares, trendy design, on-flight entertainment, and internet-based ticketing. The unveiling of "Song Sung Blue," which features a retro polka-dotted tail-fin design, was announced in a media alert sent out yesterday, with the heading, "Low Fare Carrier's Stylish New A-320 will have Competitors Singing the Blues."