I went into the city (NYC)last week to a seminar at Microsoft. Coincidently, it was on St. Patrick's Day. There were NY State troopers on the trains going in and coming out. At the M'soft building, I had to produce photo ID in order to gain access to the elevators. Either plainclothes or FBI in the lobby scrutinizing everyone. I showed 'em my CT Concealed Carry permit, because at heart, I'm a wiseass and wanted to see their reaction.
They just smiled as they handed it back.
What happens if/when you are involved in a traffic stop? In Michigan, it is recommended that you hand the officer your concealed pistol license and inform him/her whether or not you have a pistol with you.