I've now seen this scenario at a number of client sites and it's already caused quite a bit of data loss.
It is a common operation for users to want to create a copy of their production databases for test or UAT purposes. In SQL Server 2008 R2, in the Restore Database dialog, they entered the DB name, then entered the location of the file.
In SQL Server 2012, if they enter a target DB name in the dialog, then select the file location, SSMS then silently changes the DB name they have entered with the name of the DB that was backed up. If the customer doesn't notice this silent change (as is often the case), they end up overwriting their original database with an older backup.