I've reverted a bunch of wiki pages that were vandalized.
As all of these edits were performed by anonymous guest users, I've also
switched the wiki permissions to require membership in order to edit.
This isn't ideal, as it puts up a barrier to legitimate contributors,
which is why the site had been set to allow anonymous contributors.
At one time Wikispaces supported an option where you could restrict
edits to logged-in users, but not require membership. That meant that
anyone with an OpenID login (Yahoo, Google, etc.) could login and
immediately start editing without waiting to be approved for membership.
Apparently you now need to pay $5/month to get this capability.
So far the spam hasn't been substantial, so we could continue permitting
anonymous contributions, and just periodically clean up the inevitable
mess. Which is worse?
(You'd think at this point the site would be pretty static, but the wiki
is still getting a slow, but steady stream of legitimate edits.)