Place a colander in a 2-quart glass measure or medium bowl. Line colander with 4 layers of cheesecloth, allowing cheesecloth to extend over outside edges of bowl. Spoon yogurt into colander, and cover loosely with plastic wrap; refrigerate yogurt 12 hours. Spoon yogurt cheese into bowl, and discard liquid.
Stir in minced garlic, chopped walnuts, salt, pepper, and hot sauce, and let mixture stand 15 minutes. Serve dip with pita wedges.