I just read about the google sitemaps. This might be worth to support in mediawiki:
http://googleblog.blogspot.com/2005/06/webmaster-friendly.html
I have written a quick script to create a sitemap from the cur table in the xml format google expects and will see if it makes any difference.
might be good for wikipedia too, I don't know how good google is spidering wikipedia at the moment.
christof
mediawiki-l@lists.wikimedia.org