Blizzard announced a new phase in the beta, as per the article below.

New Phase of Beta
We are introducing a new beta phase with this patch and welcoming another round of testers into the game. A second Player-versus-Environment server has been launched to accommodate the thousands of new testers we are inviting into the beta. Select Beta Server 2 on the realms list to play on this server. These new testers will be selected from the pool of applicants from our initial signup period. Those who have been selected to participate in the beta will receive an email from Blizzard with instructions on how to download the client and connect to the new server. Unfortunately, we will not be able to accommodate everyone. Please do not contact Blizzard directly to inquire about your selection status; those who have been chosen to participate will be contacted by email. Good luck and thank you for helping us test World of Warcraft!