Grease and waxed paper-line 15x10-inch jelly roll pan; set aside.
In large mixing bowl, beat eggs at high speed for 5 minutes. Gradually add sugar. Reduce speed to medium; add pumpkin and lemon juice. Stir dry ingredients together and fold into pumpkin mixture. Spread evenly into prepared pan. Sprinkle with nuts on top. Bake 15 to 16 minutes, or until cake is firm in center. Remove from oven. Cool 5 minutes. Cut around edge of pan. Place clean dish towel liberally coated with powdered sugar on large flat surface. Turn cake with nuts side down onto towel. Remove waxed paper. From 10-inch side, quickly roll cake up in towel. Cover with another clean dish towel. Set aside to cool completely.
To make filling: In mixing bowl beat together cream cheese and butter; stir in powdered sugar and vanilla and blend until smooth. Unroll cake. Evenly spread filling over cake. Roll up cake (without the towel!). Wrap in plastic wrap. Cover and chill at least 1 hour. Slice before serving. Store in refrigerator.