Security Theatre

Here is a good article from Bruce Schneier talking about the ease at which airport security checkpoints can be circumvented using a fake boarding pass. I recently flew for the first time since the "liquid explosion" scare, and can attest to the inanity of the TSA and its employees; Airport security is a massive exercise in bureaucratic security theatre, and does nothing to actually improve the security of flying. If my shampoo is explosive, how does placing it in a clear one-quart ziplock bag eliminate the threat to other passengers?