I have used pre-check at 4 airports in the past two months (Dulles, Detroit, Orlando, Tampa). It is not available at all airports, nor is it available for all airlines. I have had a maximum of 4 people in line ahead of me, and it does move swiftly because you don't have to remove articles of clothing.

If you apply for NEXUS or a similar Trusted Traveler program, you have to pass a security check by the federal government and, in my case, the Canadian government.

You are still required to go through a metal detector or a sniffer, and your carry-ons run through the x-ray machine. If you carry a weapon through, they can confiscate it, charge you, and remove you from the pre-check program. They did find a water bottle in my carry-on.

Link to TSA precheck website: http://www.tsa.gov/tsa-precheck