Google, Yahoo and Microsoft now have a standard sitemap format, see http://www.sitemaps.org . I've switched the WSN Links google sitemap into this generic sitemap for 4.0.6. Your old google map will remain in place but won't update, the new map is mapindex.xml.
As of yet I can't find the url for submitting sitemaps to yahoo, so automatic submission is only to google. Microsoft is apparently going to start supporting it in "early 2007."
"Do things you love doing, because then it ain't work. Don't do something you don't really enjoy, because you're never going to work hard enough at it." - Bob Young, founder of Red Hat