Found at schneier.com
BBC NEWS | UK | Detonation of liquid explosives
This video shows the damage caused by a liquid bomb to a commercial airliner.The BBC used a qualified explosives engineer, Sidney Alford, to construct the devices to demonstrate their likely effect on an aircraft fuselage.
I am quite surprised – I didn’t think there was anything at all in this security idea that you can’t take liquids onto a plane. I suppose my next question is “does limiting to a clear bag full of liquids actually stop the risk?”
No, because there’s no particular need to use liquid explosives. The reason they were a threat originally was that most people don’t think of bottles of liquid when searching for a bomb, so they could be smuggled past security. Now that they are a suspicious item, the savvy terrorist will be going back to plain and simple PE4 or whatever. There’s still plenty of ways to hide that; off the top of my head, how about cutting a mars-bar sized block and sealing it inside a mars bar wrapper? A detonator would fit inside a pen, put openly in the little pot as you go through the metal detector. With the open tube part cut off (our suicide bomber isn’t going to crimp it onto a fuse, just stick a match in the end and head off to paradise) it would be short enough to fit inside a perfectly normal-looking keyfob too.
Airport security can stop amateur lunatics, but the defence against properly organised groups is good intelligence before they ever get to the airport. So far we seem to be managing OK with that.