OK, not much of a style guide, just one or two points so far to help keep us from going crazy...

Use [brackets] for inline edits/comments to canonical pages

If you're making an inline edit or comment on a canonical page, like one of the workshop real-time notes pages or a policy page, please put your edits in [brackets] with your name or user ID and the date.

For example, the author M.E. placed his/her comment within brackets at the end of the moving, poetic sentence below:
Blah blah blah. [the repetitive use of "blah" is inspired. You're a genius! M.E. 4/232/09]

We've been doing this on internal Smithsonian wiki pages for a while and it really helps us follow along. Most of the time these so-called canonical pages will have a note about this up at the top of the page. But if you have any doubts about this don't sweat it. The most important thing is that we get your contribution, not it's format ;)

Use yellow highlight to signify something important: green highlight to signify Action Required

I've been using yellow to draw attention to text, mostly from the workshop notes, that needs to be bubbled-up to the top of the discussion.
And I've been using green to highlight something that requires action.

To make highlighted text, enter edit mode, select the text you want to highlight, click on the Font Style button
the font style button

And set the Background Color to green or yellow.