You're actually in luck since the spammer seems to at least use the same
username - on some wikis I host he used alternating IPs and usernames,
apparently hijacked Windows machines.
You can clean up some of the mess he made using Brion's Special:Nuke
extension:
http://cvs.sourceforge.net/viewcvs.py/wikipedia/extensions/Nuke/
It allows you to mass-delete all pages created by a user IP.
You will also want to install the spam blacklist extension:
http://cvs.sourceforge.net/viewcvs.py/wikipedia/extensions/SpamBlacklist/
If someone is looking for a nice project to hack on, I think for smaller
wikis a special page that searches all current revisions for a
particular text and deletes them if it contains the text (with prior
checkbox list like Special:Nuke) would be quite workable. This could be
run repeatedly if the spammers use multi-edit attacks.
We only win the war against spammers if we make all their actions easier
for us to revert than for them to perform. Captchas would be another
tool to accomplish this.
I also believe that we should fix up the Spam Blacklist extension code
and move it into MediaWiki proper, perhaps using a Poor Man's Cron in a
deferred update to get the Wikimedia blacklist every 24 hours. Spam will
be a problem for _every_ public wiki sooner or later and I can see few
good reasons to have this functionality only in an extension.
Erik