A couple of times I have had to make very last minute flights for business purposes, and have accidentally gotten through security at several different airports with pocket knives, long pointy scissors, and even a box cutter once, in my brief case. Had no idea they were there until I got to my destination and started taking things out. Kind of scary that I was able to get all of those things through on multiple occasions at multiple airports. I wonder if it made a difference that I was wearing my SIDA badge, and the screener didn't really feel the need to thoroughly search my bags or something. It shouldn't make a difference, at least. Since, I have made it a point even on a last minute flight to go through things when I park at the airport just to make sure; I can't afford usually to be detained by police for attempting to take a prohibited item into the secured area.
TSA certainly looks like they're doing something, but exactly what that something is, is up for debate.