One of the big changes in the SQL Server 2012 licensing plans is the price is now per core, and not per processor. So previously if you had a SQL Server with 2 procesors (8 cores each), you paid for 2 licenses. Now in that same scenario, you would pay for 16 core licenses. Although the core prices are less than processors pricing, if you have a 4 core processor or more, it will end up costing you more. Also, there is a minimum of 4 cores for any SQL Server license.
For many configurations this is going to dramatically increase the licensing costs of SQL Server.