All search crawlers recognize robots.txt, so it seemed like a good idea to use that mechanism to allow webmasters to share their Sitemaps. You agreed and encouraged us to allow robots.txt discovery of Sitemaps on our suggestion board. We took the idea to Google and Microsoft and are happy to announce today that you can now find your sitemaps in a uniform way across all participating engines. To do this, simply add the following line to your robots.txt file:
Sitemap: http://www.example.tld/sitemap.xml