Ian, I like this a *lot*. However ReST on its own is YAWML, so you might want to make a couple of modifications to it. Certainly more casual visitors to the wiki will probably appreciate being able to input both WikiNames and [[Bracketed Wiki Names]]. You could alwyas pre-process them into ReST before passing it on to the parser, and store the ReST form.
I've added a sandbox, linked to from the "This Wiki" page.
One thing I've found quite useful on some of the newer wikis that I've come across is a checkbox that allows the authors to state "this is a minor change". This allows people to come in and correct typos and whatnot without it triggering a new entry on RecentChanges which will be undetectable to the naked eye, and rather a downer when viewing the subsequent diff. It would still appear on the page history.
Other possible changes:
Viewing a diff might be nice.
Having a link to "view current version" on the bottom when viewing a history entry
Writing some docs on how to include an image would be nice.
I'll see if I can have a look at doing these in my Copious Free Time this evening...