There have been a couple recent enhancements to sitemaps that everyone should start using.
The first is that Google now supports embedding kml data into sitemaps. This allows you to provide a hint as to where information is related to geographicaly as well as more detailed information to be used in popups on the map. For more information on how to make the integration see the maps sitemap API page. We already support sitemaps in our content management solution and we will be integrating this new mapping feature as well.
The second new feature added has to do with getting your sitemap included in search engines. Now all search engines that support sitemaps will inspect your robots.txt file for a pointer to your sitemap. This should remove the need for everyone to submit their sitemap to every search engine. You may still want to submit your sitemap because there are nice tools from engines like Google that let you investigate more information about your site but now you won’t have to if all you are looking for is your site to be crawled correctly.