Thanks for your reply Mary.
The hurricanes seem like a good connection point, especially given New Orleans' French heritage. We've had a fair number of "hurricane transfer" students entering schools here and I expect they could tell some stories.
I had another thought - my wife teaches at a high school that is just beginning an international studies "magnet" program. (You may have run into another local Atlanta magnet school - Wheeler HS - at the robotics competition. They're heavily into that and, coincidentally, that's where my daughter met her French (now ex-)exchange student friend.)
It strikes me that your experience at Aiken High could be useful to them. Their only online systems at the moment are e-mail and a Typepad blog, which they are just now implementing. However, I put up a Moodle site for my wife and am hopeful that this seed might take root there.
Your idea of a kind of Moodle exchange program is a good one - do you know if the community here has addressed this in any kind of a deliberate way as yet?
Thanks again for your insights,
PS - Sorry - had another thought about the class - have you considered creating PodCasts, videos, or using Skype-miniconference calls to get your kids engaged with their counterparts? Might not help the writing aspect, per se, but could get them connected...