Beat butter and cream cheese at medium speed with an electric mixer until smooth. Add flour and salt, and beat until blended.
Shape dough into a ball; cover with wax paper, and chill 1 hour.
Cook dates, sugar, and 1/4 cup water in a saucepan over medium heat 3 to 5 minutes or until thickened. Remove from heat; stir in walnuts and orange rind, and let cool.
Divide dough in half. Place 1 portion on a lightly floured surface, and roll to 1/8-inch thickness. Cut dough with a 2 1/2-inch round cutter, and place on a lightly greased baking sheet. Spoon 1/2 teaspoon date mixture in center of each cookie. Repeat procedure with remaining dough.
Fold dough over filling, pressing edges with tines of a fork to seal.
Bake at 375° for 15 minutes or until lightly browned. Sprinkle with powdered sugar.