Line a greased 15x10x1-in. baking pan with waxed paper. Grease the paper; set aside. In a bowl, beat eggs for 3 minutes. Gradually add sugar; beat for 2 minutes or until mixture becomes thick and lemon-colored. Stir in pumpkin and lemon juice. Combine flour, cinnamon, baking powder, ginger, salt and nutmeg; fold into pumpkin mixture. Spread batter evenly in prepared pan. Sprinkle with walnuts.
Bake at 375° for 12-14 minutes or until cake springs back when lightly touched in center. Cool for 5 minutes. Turn cake out of pan onto a kitchen towel dusted with confectioners' sugar. Gently peel off waxed paper. Roll up cake in towel jelly-roll style, starting with a long side. Cool completely on a wire rack.
In a bowl, combine filling ingredients; beat until smooth. Unroll cake; spread evenly with filling to within 1/2 in. of edges. Roll up again without towel. Cover and refrigerate for 1 hour before cutting. Refrigerate leftovers.