All three companies will use the Google Sitemaps protocol.

“In the first joint and open initiative to improve the Web crawl process for search engines, Google, Yahoo and Microsoft today announced support for Sitemaps 0.90, a free and easy way for webmasters to notify search engines about their websites and be indexed more comprehensively and efficiently, resulting in better representation in search indices,” a joint news release said”.

The protocol is also open to other search engines.