"There are quite a few wiki engines out there that are backed by a distributed version control system. This means you can easily edit them online using the browser, but also checkout the repository and work with the files in a local text editor. I am working on getting one of these wikis LaTeX and MathML enabled as a possible solution for collaborative paper authoring. I can't solve the hosting problem, but I intend to make the installation as painless as possible, including on cheapo shared hosting accounts.Adapting this to a provide a simple engine should also not be too difficult, although it would not have all the features of Wordpress." - Matt Leifer