But that doesn't meant you can learn! It's meant to use something like gs-proxy.
I don't have an instance of gs-proxy running for this, just take a peek at the injected JavaScript.
The published spreadsheet is located at https://docs.google.com/spreadsheet/pub?hl=en_US&hl=en_US&key=0AmYzu_s7QHsmdE5OcDE1SENpT1g2R2JEX2tnZ3ZIWHc&output=html