Comment Microsoft figured this out already (Score 1) 228
I just gave my 12 year old a Windows Phone. Needed to create a Live/Hotmail account (for Skydrive file syncing, Xbox avatar, purchases, etc). When entering her real birthday it prompted for parents email address. I received the email and needed to prove that I was over 18 by letting them charge 50 cents to a credit card. Total time involved -- maybe a couple of minutes. Of course this is not foolproof -- no way to prove that the 18 year old is really the responsible guardian but I bet this is enough to protect Microsoft from COPPA violations.