Ken Moss, General Manager of Live Search, announced today that Microsoft, Google, and Yahoo! will all support the SiteMaps protocol, a simple, xml based way for web site owners to share information with search engines without having to rely on crawl algorithms. Ken describes the work Microsoft is doing:

We are 100% behind this protocol – this kind of collaboration will help improve the search experience for all of our customers, and we are working hard to release full support in 2007. 

Ken points to SiteMaps.org, which has some details on the protocol:

Sitemaps are an easy way for webmasters to inform search engines about pages on their sites that are available for crawling. In its simplest form, a Sitemap is an XML file that lists URLs for a site along with additional metadata about each URL (when it was last updated, how often it usually changes, and how important it is, relative to other URLs in the site) so that search engines can more intelligently crawl the site.

Web crawlers usually discover pages from links within the site and from other sites. Sitemaps supplement this data to allow crawlers that support Sitemaps to pick up all URLs in the Sitemap and learn about those URLs using the associated metadata. Using the Sitemap protocol does not guarantee that web pages are included in search engines, but provides hints for web crawlers to do a better job of crawling your site.

And Google provides quite a bit of information in Webmaster Tools, including a sample of the xml:

With relevance in Search getting to be more and more of a commodity, this move to work on standards for search can only be seen as a good thing.