[youtube]http://www.youtube.com/watch?v=_XOY7lsBVpo[/youtube] In her only concert this year, Janet Jackson headlines the opening night of the Essence Music Festival at the Louisiana Superdome. Since the festival’s inception, Frankie Beverly and Maze have closed the festival; this year, Earth, Wind & Fire follow Mary J. Blige Sunday for a festival-ending dance party. Here they are doing “Let’s Groove.”