Sitemaps are not a novelty. They have always been part of best Web design practices but with the adoption of sitemaps by search engines, now they become even more important. However, it is necessary to make a clarification that if you are interested in sitemaps mainly from a SEO point of view, you can't go on with the conventional sitemap only (though currently Yahoo! and MSN still keep to the standard html format). For instance, Google Sitemaps uses a special (XML) format that is different from the ordinary html sitemap for human visitors.