Google, Yahoo, MSN and Ask (new on board) then should fetch and parse the XML sitemap automatically. Next week or so the cool robots.txt validator will get an update too.
Question: Is XML Sitemap Autodiscovery for Everyone?
More info here.
Q: Does it work by user-agent?
A: Yes, add all sitemaps to robots.txt, then disallow by engine.
Q: Must I fix canonical issues before I use sitemap autodiscovery?
A: Yes, 301-redirect everything to your canonical server name, and choose a preferred domain at Webmaster Central.
Q: Can I submit all supported sitemap formats via robots.txt?
A: Yes, everything goes. XML, RSS, ATOM, plain text, Gzipped ...
Tags: Search Engine Optimization (SEO) Google Sitemaps robots.txt Yahoo MSN Ask
Post it to