It's been a while since I was on here (my life would be great if it wasn't for all the work getting in the way)...
Just wanted to refresh this topic as I did travel through France for over 2 weeks with my BB8100 and used TeleNav constantly. Upon my return I got my bill from Cingular and there were no extra data charges for my Internet/TeleNav use while there. Therefore I would say that the International Blackberry Plan includes not only email but unlimited Data as well.
BTW - TeleNav was fantastic for touring around. I did over 1200km during the week and a half I was in the south of France and it was a life-saver - "Enter Roundabout and take the 3rd exit" is so much easier than going in circles, trying to read street signs, watching for cars entering/exiting the roundabout all while listening to your wife tell you your going the wrong way. I also used it in Paris using "Pedestrian" as the method for determining the route.
All around I'm a happy camper with my 8100/TeleNav