No Bobski, you're not allowed to lock your luggage anymore.
They have checked luggage screening stations at the airports. For the trip down, they opened all of our bags. At our airport, the security agent scanned the contents and every pocket with what appears to be a small white strip of paper. What it actually does is detect the presence of explosives. (My DH works in a secure facility and explained it to me because I was clueless.)
We checked our luggage at Port Canaveral for the return trip, so I don't know what happened to them from there.
I've already mentioned using key rings on the Transportation board because cable ties require something to cut them open. That can be a real problem since you're supposed to pack sharp instruments in the checked bags. Someone responded with facing that very dilemna, and it was very inconvenient.