Actually it is growing at a very fast rate. 5Million listed for the region. 500,000 listed as actual residents. Atlanta has a HUGE suburban area that commutes to Atlanta. Their is a big push to ad bike lanes (the gov figured out that they get money from the feds).
http://en.wikipedia.org/wiki/Population_of_Atlanta The region grew by 1,000,000 in 7 years.

The Critical mass here regularly draws 500+.
http://www.youtube.com/watch?v=z7BVVB2e5N0
And thats only a small sampling as a lot of daily riders will not participate in Mass because they feel it gives a black eye to the community with the corking actions.

As for market. Talked to the sales person at REI yesterday when I went to get the light I wanted. They can't keep them on the shelf. Somebody buys them.

I ended up spending $100 on lights, reflective stickers and a vest. Lost sale for the LBS three miles away that I honestly left the REI so I could try to spend my money with them and had to go back to REI a day later to get what they didn't carry.