I had my multi at the belt when I travelled across USA in a pre-9/11 2001.
No problem anywhere, even at the Pentagon or at the White House tour. I had only to show it to the security before entering metal detectors in such places.
Now, I really hope that, even after Patriot Act, no law-enforcement officer could see a plier, or a not-so-long knife you usually need two hands to open, as a menace...