The official SQL Server AlwaysOn team blog.
Writer: Cephas Lin (Microsoft)
Contributors: Sanjay Mishra (Microsoft), David Smith (ServiceU Corporation), LeRoy Tuttle Jr. (Microsoft)
Technical Reviewers: Prem Mehra (Microsoft), Mike Weiner (Microsoft), Steve Howard (Microsoft), Kun Cheng (Microsoft)
Summary: Using Failover Cluster Instance (FCI) for local high availability within a data center and augmenting it with Database Mirroring (DBM) for disaster recovery has been a very popular HA+DR solution. With SQL Server 2012, this FCI+DBM solution can be replaced with a FCI+AG (Availability Groups) solution. This whitepaper describes how to migrate an existing FCI+DBM solution to a FCI+AG solution.
Read on: http://msdn.microsoft.com/en-us/library/hh923056.aspx