The official Google Webmaster Blog 
reports that 
Yahoo and 
Microsoft will support the sitemaps protocol created by Google to facilitate site indexing.
At the moment, the protocol is assigned a new version number - 0.9, and the documentation for creating “site maps” is posted on the new site - 
sitemaps.org . Sitemap is a file in XML format, containing the URL of all pages that are available for indexing by search engines.
Site creators can offer "site maps" to search engines using special pages - 
for Google , 
for Yahoo .