Searching for pastry crust recipe made with creme fraiche
If you look at the photo on page 38 of the Nov 2008 issue of Gourmet, you'll see that Nancy Pomeroy, owner of a restaurant in Portland, OR, is pictured in front of a recipe for creme fraiche dough. The ingredients include baking powder, though, so I'm not sure it's a pie crust--I don't know what kind of pastry you plan to make.
I've made pie crusts using sour cream to bind, instead of ice water. The dough is shaggier than when you use liquid. I've also used buttermilk to bind, which makes the crust more tender than using water. My standard recipe uses a ratio of flour:shortening of 2:1, and I always start with 2/3 of the recommended amount of binder and work up from there, if necessary.