Yahoo! and Microsoft have joined Google in supporting the Sitemap protocol. The Sitemap protocol, which was started as an experiment was published by Google last year under the Attribution/Share Alike Creative Commons license. Google claims the experiment is still underway.

Sitemap 0.84 XML protocol is a free and easy way for webmasters to inform search engines about URLs on their web sites so that search engines can more effectively crawl them. As the web becomes more dynamic, Sitemaps will enable better and fresher search results for everyone who uses the web. For site owners, Sitemaps will help improve website visibility in search results.

As part of this development, the protocol has been moved to a new namespace, www.sitemaps.org, and the version number has been raised 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, it will continue to be accepted. If you haven't submitted a Sitemap before, check out the documentation on www.sitemaps.org 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.

And if you're a critic of Google Sitemaps, here's something for you.