We're thrilled to tell you that Yahoo! and Microsoft are joining us in supporting the Sitemap protocol.

As part of this development, we're moving the protocol to a new namespace, sitemaps.org - Home, and raising the version number to 0.9. The sponsoring companies will continue to collaborate on the protocol and publish enhancements on the jointly-maintained site sitemaps.org.

If you've already submitted a Sitemap to Google using the previous namespace and version number, we'll continue to accept it. If you haven't submitted a Sitemap before, check out the documentation on sitemaps.org - Home for information on creating one. You can submit your Sitemap file to Google using Google webmaster tools. See the documentation that Yahoo! and Microsoft provide for information about submitting to them.

If any website owners, tool writers, or webserver developers haven't gotten around to implementing Sitemaps yet, thinking this was just a crazy Google experiment, we hope this joint announcement shows that the industry is heading in this direction. The more Sitemaps eventually cover the entire web, the more we can revolutionize the way web crawlers interact with websites. In our view, the experiment is still underway.

Official Google Webmaster Central Blog: Joint support for the Sitemap Protocol