Jennifer Higdon won the Pulitzer Prize for Music on Monday. A few months ago, she won a Grammy. Jennifer lived here till she was 10, so I think that qualifies her as an Atlanta Composer. ;) She's also been commissioned by the Atlanta Symphony and is premiering a new work here with eighth blackbird in June.
Mark Gresham wrote a piece on her a while back. I think it was for her 'Atlanta' piece, City Scapes. (Mark, do you want to post a link to that?)