I'm not sure what else they do at Dragon*Con in Atlanta besides show off their amazing costumes - as I read on someone's Twitter status, "[San Diego] Comic Con is for amateurs" - but thanks to Brainiac 5 there was a gathering of Legionnaires (and a villain or two) at this year's convention. Pictures are slow to come online but I found a few.
@ThatDJSpider showed off her Sensor Girl costume before the con (original source; more of her shortly):
Here's a link to another photo at a DC character gathering. Lightning Lad is on the far left. This one has Brainiac 5 (the one who organized the Legion shoot) and Kid Quantum. (Note that neither of these allows pictures to be hotlinked like the one above).
Here are Brainiac 5 and his wife Supergirl.More photos on the Superhero Costuming Forum (which has its own discussion area just for Legion costumes).
So here's Sensor Girl (not hotlink-able) - and you know, I think that's what Sensor Girl would really look like.
And here are the 15 costumed Legionnaires and villains from this year's photo shoot, via @Gary_TheGreat (original source):
Gary posted one other picture, taken after Keith Giffen left the area (original source):
Still waiting on others to be posted.