The licensing model is changing for SQL Server this year 2012. CPU licensing and server/cal is going away for enterprise. licensing is moving to per core with a minumum of 4 cores per cpu and all cores must be licensed. For vm, all cores in the farm must be licensed and you must have software assurance or each guest can be licensed with a minumum of 4 cores per guest.

standard will still have server/cal, but maxes out at 20 cores

data center and workgroup will no longer exists

web will be for hosters only.