I thought it might be a good idea to update this old thread. Apparently, GA state law was changed, effective 7/1/2012, it is now legal to carry up to five inches.
Also, I wanted to tell of you my experience.
In 1991 I was carrying an older Buck light, in a sheath on my belt, when I went to the ER one night with a migraine. It was the smaller version, with a <3" blade, and just a little over 7" overall when open. The guard asked for it, and I surrendered it to him, letting him remove it from the sheath. (I carried it with the Velcro flap stuck back in the open position, so the top half inch or so was visible and easy to grasp.) The ER was crowded, and I soon decided to leave without treatment. He gave it back to me wrapped in a postal envelope, with a bunch of scotch tape wrapped around that. Rather than deal with the tape in my condition, I just shoved it in my pocket and left. Hours later, my conditioned having worsened, I returned. I was sitting at Registration, with my head down on my crossed arms on the counter. The officer walked up beside me and asked for the knife. I started to "present" the sheath to him as before, to let him remove it, and then realized the knife was still in my pocket. I took the still wrapped up knife out of my pocket, handed it to him, and put my head back down. A short while later he was back....... with a patrol officer.
I was accused of "drug seeking behavior" and taken the the state hospital. I filed for an AMA release, and they responded by starting commitment proceedings. While I wasn't actually charged with a crime, there are probate court documents on record that state that I threatened the ER staff with an open 10" knife. I spent 23 days locked up with real crazy people, some dangerously so, before a second doctor realized I didn't belong there and released me. So I now have a record that eventually cost me my firearms license, and the ability to purchase a weapon from a licensed dealer.
I realize that I might have had a chance to refute those accusations in a criminal court (probate court does not recognize the right to confront witnesses, or their written statements), but my point is that they can measure however they want, and claim whatever they want.
And even if criminal charges don't stick, you could still be arrested...... or worse.