Robert Oschler wrote:

> Because of the Google Page Rank land grab, there are web sites running
> scripts to deface popular Wikis with links to their site. For a dramatic
> example look at the Revision history page for the Ruby Garden Wiki:
> 
> http://www.rubygarden.org/ruby?RecentChanges
> 
> The problem is, even though, we diligently delete the spam as it shows up,
> most Wikis archive the old revisions in a revision list. Google (you) crawls
> these revision list pages and finds the deleted spam links. In fact, you
> find a lot of them because the spammers keep coming back and we keep
> deleting them, creating lots of revision history pages that you crawl.
> 
> Here's a VERY SIMPLE way for you to help out the thousands of Wikis out
> there.

robots.txt ?

Google adheres to that very strongly. and I notice there's no 
http://www.rubygarden.org/robots.txt

http://www.google.com/webmasters/faq.html#norobots

- Greg