Yahoo has their own version of Google Webmaster Tools, called Yahoo Site Explorer. Site Explorer lets you notify Yahoo of your sitemap files, web feeds, etc. to help facilitate faster indexing.
Many webmasters discount yahoo in their search engine marketing efforts, since Google has emerged as the clear winner of the search wars. The problem is that one fifth of U.S. web searches still use Yahoo. So it’s probably worth heading over to the “Yahoo Webmaster Tools” to submit your sitemap.