Should be able to restore. If you look on the left, it has a link to "recent changes" and you can look at it before it was wiped: http://wiki.planetisuzoo.com/index.php? ... oldid=1150
It looks like the main page was blanked, but all the linked pages are intact. Though it was my first look at the Planet's Wiki site so I don't have a frame of reference regarding any changes.
Restoring pages on the wiki should be fairly straight forward. MediaWiki is basically a versioning system at it's core, so if someone with Admin rights/privileges logs in, they should be able to revert the affected pages without too much issue. It's been a while since I've maintained a wiki, but I think you can be as fine grained as you want when reverting versions from the top down.
I haven't had a chance to go look, but it may have been restored or had the changes "undone" already.
To the admin:
I wrote a backup script that gets a database dump (backup) every night, and maintains the last seven days of backups separately. They automatically roll off after seven days. If you are on Linux/MySQL, and you're interested, holler at me.
I've got something similar from a while ago, although I think mine takes two dates (begin and end) and replays the transactions and such from that time period assuming you have a cron job to copy the logs to another location. But your backup script sounds like a much better solution for this task.