I THINK gifted qualification carries over in Cobb, but I am not certain. The city of Marrietta has a separate school district from Cobb County. Web sites are
http://www.cobbk12.org and
http://www.marietta-city.k12.ga.us. Cobb county also has an active chapter of the Georgia Association for Gifted Children,
http://www.cobbchapter-gagc.org.In Elementary school, Cobb has pullout program once a week for Gifted students. Some schools also do some compacting for math and grouping by capability. In-room differentiation is also encouraged but you may need to keep an eye on things.
The middle schools offer up to 4 gifted classes. Language Arts (writing), Science, Social Studies and Math. Placement is based on 5th grade testing and, to some extent, space.
High schools offer Honor classes and AP classes. Since we are not there yet, I don't know the details. There are also Magnet programs in various disciplines and an IB (International Baccalaureate) program.