Hello from Virginia!
I had for a while attempted to put together a gifted kid play/parent chat group, however wasn't able to stir much interest in it, even with folks I know. I think there is one closer in to d.c., in fairfax area, however.
Other than that, the only advocacy or efforts I've made have been specifically for my own kids, reading about identification, dealing with having children correctly identified or not, 2e issues, etc.
Learning early about your own school district's early entrance and gifted program possibilities is one good thing about tuning into the whole thing while your kids are relatively young. Just in case it does turn out that they have unique educational needs.
Hoagies.com is another great site for reading and re-reading. Also, you might be interested in googling on 'levels of giftedness' a concept put forward by Dr. Ruf, trying to identify and suggest what will be needed to educate children at the different levels of giftedness: kids who are gifted can vary a LOT in their actual abilities/potential.
Best of luck and welcome!