I have run into a situation on my servers where our service broker setup for query notifications has begun producing deadlocks. The situation is described perfectly in this KB: http://support.microsoft.com/kb/975090, however we're on SQL Server 2012 SP1, not 2005/2008. I can see from the deadlock information that these internal queries for sys.query_notification are most definitely NOT using serializable isolation level, they're all read_committed.
Is there a reason why SQL 2012 has regressed to this type of behaviour?