A document has been created that can be used along Microsoft Assessment and Planning (MAP) Toolkit to help customers determine SQL Server 2012 core licensing requirements for their deployed SQL Server databases, specifically at the time of their Software Assurance renewal.
For more information, see the MAP Toolkit blog at http://blogs.technet.com/b/mapblog/archive/2012/04/25/determining-sql-server-2012-core-licensing-using-the-map-toolkit.aspx