The Cataclysm beta character copy page is available for those select few who have keys. Our understanding is this is a very small group. You'll know that you have a key and can copy your character over. If not, then you're not in it, yet. Don't fall for any scams.

Blizzard has not announced the opt-in procedures or any ways to get into the beta. When they do announce it, you'll hear it here.

The page is accessible at: https://www.worldofwarcraft.com/beta-charcopy/

UPDATE: Zarhym has confirmed the Cataclysm Friends and Family Alpha begins this week.