I'd like to also add my thanks. Great work.
I think a very visible last updated date and the "applies to" section would be great.
When I first started using nginx and the wiki, I found one thing a bit confusing. Clicking on a link on http://wiki.nginx.org/Modules directs you to the corresponding page on nginx.org/en/docs. While it's great to be directed to those docs, I expected to be taken to a wiki page on the core module. I would suggest some kind of notice that these links will take you to the nginx.org/en/docs site.
The obsoleted pages are difficult. A link like this http://wiki.nginx.org/CoreModule#error_log in a google search bypasses the notice at the top so whoever's reading has no idea that the page has been obsoleted. I'm not registerd on the wiki so I don't know what editing options are availble to offer any suggestions for dealing with this.
Terry