This is similar to what we are building at UserDeck. We call it Guides and it is a knowledge base widget that embeds inline into any page of a website. It is all Javascript and customizable on the client side with layouts and components which have options which let you change things like a sidebar component to the right side instead of the left.

Any team member can collaborate and edit articles live on the site and we are considering adding wiki type functionality if people are interested.

You can learn more at http://userdeck.com/guides.