Hi Sarah, It's a cool feature but isn't strictly speaking a "style guide" - since these are typically documents created by the design team as the website/collateral/kiosk/etc is in the process of being designed.

This is useful for discerning details about an existing, already designed website but won't be much good for a designer trying to impress a new client since he's using their existing website. Unless, that is, he's trying to sell them on keeping the old one and not hiring him!

:)