hi, i was just taking a real good look at the www.google.com/robots.txt and i found this little gem in there

  Sitemap: http://www.gstatic.com/trends/websites/sitemaps/sitemapindex.xml 

besides that fact that google killed on of their more usefull tools (google trends for websites) it seems they forgot the tell the robots.txt team (if there is such a thing)