Huck you are wrong. Pre 9/11 there was no check at all for Domestic Flights. Your friends could accompany you unchecked to the gate. I know because I have done it.
And the security for domestic flightss is different as Mr Broughten says. Last week on a domestic flight from SFO my laptop stayed in my carry on bag. On the subsequent International flight out of LAX my laptop was taken out of the bag by the TSA man and put through the X-Ray seperately. (I, because of my experience in SFO, had left it in the bag.)