I say, for leveling there is no reason to go much beyond this in frost:
http://www.wowprovider.com/?talent=1121 ... 03102351c1as there are too many people to effectively AoE anywhere. If you /really/ want to Frost TO ELEVEN, I guess you could fill out Permafrost and Winter's Chill, but as far as I'm informed, you are much better off smacking some points into Arcane... even though damage is rather low over there. Come to think of it, all I've ever heard was at 40 you should start using the talents you will be using at 60, and since I've never leveled a vanilla mage to 60, I'm wholly unqualified to give a proper answer! Why am I still typing!
Either way, there should be plenty of time to learn at 60, so level with what you want, I say!