Freezing Cake Batter
I don't think a cake batter made with baking powder or baking soda would freeze well. They cause a cake to rise and the effect would be lost if it sits.
Also, I wouldn't freeze a batter that has beaten egg whites, like an angel cake or a chiffon cake. For similar reasons. The egg whites lighten the cake and the airy-ness would be lost as the batter is frozen and then thawed.
Not sure about other kinds of cakes.
I know that muffin and quick bread batters freeze fine and they are very similar to many traditional butter cakes.
No first hand experience with cake batter though. I have never thought about freezing cake batter. As stated by others, bake then freeze has been the way I have always done it.
But give it a try with a heavy batter sort of cake I bet it will work.