This is a shadowy and secret page that only people are are "Known" to the wiki can edit though that everyone can view.
It's basically a test of moinmoin's new ACL support.
See HelpOnAccessControlLists for more information.
I've also created an ACLTestUnreadablePage that only known users can read to see what that looks like.
Note, I'm not intending to destroy WhyWikiWorks by using this though it might mean I keep private todo lists on here more now.