Microsoft announced the commercial availability of subscriptions for the Windows Azure platform, which includes Windows Azure, SQL Azure, and Windows Azure platform AppFabric.
Customers with Community Technology Preview (CTP) accounts who wish to continue usage of the Windows Azure platform must upgrade their accounts prior to February 1, 2010. New customers can start using the services by signing up for one of the paid subscription offers.
You can read more about the annoucement over here
If you are an MSDN subscriber, then read this Windows Azure Platform Benefits for MSDN Subscribers