Grease and flour 3 9" round cake pans. Preheat oven to 350°.
In a large bowl, whisk together the gelatin, sugar, flour, salt, baking powder, and baking soda.
Add eggs, oil, orange juice, lemon juice, and vanilla. Mix well with electric mixer.
Divide batter among 3 pans and bake for 25-35 minutes. Cake will be done when toothpick inserted in the middle comes out clean.
Allow cake to cool for 10 minutes in pans and then turn out onto cooling rack.
While cake is still warm, mix key lime juice and powdered sugar and gently pour over cake layers. You can gently pierce the cake with a fork before doing so, but is not necessary. Allow cake to cool completely before frosting.