Aviator and Grand Slam - I agree completely. Unfortunately, I doubt the buerocrats will ever let us (pilots) carry a gun in our flight bag. They broke off the 2" file on my nail clippers this weekend. And I was in uniform.
Stun Guns sound good to the public but will not be effective for the reasons so well described in this thread.
I have to admit, I was dissapointed when I heard the head of ALPA make a case for guns in the cockpit (on the Larry King show) with the restriction of a two week training course at a military facility first. I think any short course (one day) would be fine. Or, simply being licensed to carry a conceiled weapon ought to be enough. As it was said earlier, this is a three foot range shot. And the deterrent of knowing some pilots have guns would probably eliminate most of the problem before it ever started.