John Hargrave has discovered the secret to getting your deadly liquids onto an airplane, even if they're in bottles larger than 3 oz (the vessel size at which all liquids become high explosives, unless they are purchased at a duty free store).
All you need to do is surrender the bottle at the screening station, wait for the the TSA to throw it away in an unguarded trash-barrel on the "secure" side, and then retrieve it from the trash.
Hargrave is the same character who smuggled a quarter-ton of electronics into the Super Bowl and cleared TSA security with a live vibrator in his pants.
The reason this "smuggling" technique works, of course, is that liquids aren't dangerous. Everyone knows this — even the TSA. That's why they don't guard the barrel after they confiscate your wine, water, and salad-dressing. The point of taking away your liquid isn't to make airplanes safe, it's to simultaneously make you afraid (of terrorists with magic water-bombs) and then make you feel safe (because the government is fighting off the magic water-bombs). It's what Bruce Schneier calls "security theater."
I took my time packing up my things, watching her wrap the bottle loosely in the paper and drop it into the trash barrel.
I looked around casually. There weren't very many TSA agents servicing the area, and they were joking around, screening oncoming passengers, watching the X-ray monitor. Everyone's attention was focused elsewhere. No one was watching me.
I moseyed over to the walkway and glanced in the barrel. It was filled with half-empty coffee cups and discarded water bottles. There, on top of the trash, wrapped in its protective paper, was my salad dressing…
Calmly, I reached down into that unstable barrel of atomic liquid and grabbed my salad dressing. Then I calmly boarded the moving walkway, and stuffed the salad dressing down my pants. The TSA lets you keep things there, apparently.
Update: Many readers have written with remarks to this effect: "I wanted to let you know that there's an even easier way to smuggle liquids through airport security – put the item in your pocket. As long as the liquid isn't in a metal container it won't set off the metal detector and you have to really screw up to get patted down/searched. I fly frequently and usually take a bottle of water with me in my cargo pants. I've never had a problem with the TSA nazis."
Update 2: Thor sez, "Just a quick comment that my friend tried this liquid smuggling method a few months ago, on a flight out of Puerto Rico, and was summarily taken into a small room, given all sorts of strange gestapo-like treatments for 3 or 4 hours (they would bark at him in Spanish, switch the lights off and leave him in the dark, etc.), and finally allowed to leave after giving them all his information.
6 weeks later he received an official notification that he was being fined almost $10,000 by TSA.
He's still sorting it out with his lawyer, and his research into it seemed to imply that TSA is all about fines these days to fund its increasingly expensive and time-consuming exploits.
So try this smuggling technique at your own risk."