I mentioned some of this briefly on the IG wiki but basically there are two major aspects to wiki-style editing. One is the formatting and the other is the creation of new pages. I've set up wikitools and flexifilter.

Wikitools (as you can see from its project page) handles links that don't exist. When a link is clicked on that goes to a non-existent page, Wikitools can allow the user to create it. I may also need to include the freelinking module in order to get simple links for text in square brackets (whether or not the node exists).

Flexifilter is supposed to handle Mediawiki-style markup. This allows things like lists that start with just an asterisk, or using single quotes to mark text up for bold or italics. The problem I ran in to with flexifilter is that it's meant to handle a lot of other filter tasks and the Mediawiki formatting is just meant as an example. It links all text in square brackets to Wikipedia. Because of this I'm either going to try the pearwiki filter module as a replacement or just tweak the flexifilter module.

Besides these modules, I've also installed the Diff module to make it easier to compare revisions. Revisions in Drupal arent' created automatically. There's a box to tick (labeled "Create new revision") when editing a page. I've set this to default as checked for Book pages since that's where I expect we'll collaborate in this way. The Diff module does nice highlighting for differences when comparing these revisions of a particular page.

These modules enhance editing pages but I don't think we need them to be there to get started on writing some content. Anyone can create the new nodes as they need. If it's a large amount of content with a hierarchical structure then I would recommend creating the nodes as Book pages. Freeform content can just be created as a Page. News-type items should use the Story node type. Each of these content types is still a "node" in Drupal terminology and each can individually have comments turned on or off and can have revisions tracked. The differences are really in the idea of which content should show up in which feeds, what should move across a "news" section on the front page (or wherever news ends up), and how users should expect comments to be treated.

For example, Forum topics are also nodes and a user would expect them to remain as-is forever in general. Book pages, on the other hand, may occasionally be rewritten and have concepts from comments incorporated into the Book page and old comments deleted.

At present, there are two menu items on the top right of the site, Images and Scripts which link to books. If someone starts on a book, such as the SVG DOM reference, it's easy to edit that menu and point to the new book.