If Statesboro can have something like a literary Hannah Montana, its own iCarly of young adult literature, Maya Van Wagenen, 15, author of “Popular: Vintage Wisdom for the Modern Geek” appears headed for that level of teen celebrity.But it’s hardly a case of secret stardom. The Statesboro High School sophomore appeared on NBC’s Today Show for the book’s April 15 launch, and news of her recent and rapid literary success has been carried by Cosmopolitan, USA Today, and People magazine, among others. Her movie deal isn’t just talked about; it’s real, and with Dreamworks at that.