Please take a moment to read Carolyn Coil's recent guest-post on CNN's Schools of Thought blog:
My view: Ten myths about gifted students and programs for gifted
(CNN) – American educators have struggled for more 
than 40 years to define giftedness. Yet even now, there is no 
universally agreed upon definition of what it means to be gifted. U.S. 
federal law defines gifted students as those who perform or who show 
promise of performing at high levels in any one of five categories: 
general intellectual ability, specific academic aptitude, creative or 
productive thinking, leadership ability or visual/performing arts.