Recently Google, Yahoo and Microsoft all agreed upon a Sitemap protocol that Google has been supporting for some time now. This is an awesome development to see the big three in search agreeing on things, because it makes things easier on Web developers and Online Marketers. Today it seems like when you target one search engine you at times harm rankings on the others. I hope this is the first of many standards that are established to help ease that problem. There is no reason that you shouldn't have one on your site to help search engines crawl your site. I even see the smaller search engines following in the near future and supporting the same protocol.
