When we were in Saigon, last year, we saw a few uses - I've been meaning to do some experiments at home, but have not gotten around to it. In one area, they put the rice papers out on racks either at night, or very early in the morning, and allow the morning dew to soften the rice paper. They don't get as soft and flexible as if dipped in water, and they have a slight but pleasant chew. It is great to use as a taco of sorts - add various meats, veggies, herbs, etc. and then dip into some kind of watery (consistency-wise) sauce. You can also take the slightly softened papers, but them into quarters and deep fry them for a very nice snack.
Now, I think it goes without saying that no one I know is going to go through the effort of trying to soften the papers using the morning dew... my experiments were going to be to try to mildly steam them in a low temp. steam environment....
ETA: we're going back to Vietnam (central Vietnam this time) in late June/early July - maybe we'll get some ideas then?